DEFINITION ex1_ty3()
TYPE =
       ∀g:G.∀u:T.(ty3 g ex1_c ex1_t u)→∀P:Prop.P
BODY =
        assume g: G
        assume u: T
          we must prove (ty3 g ex1_c ex1_t u)→∀P:Prop.P
          or equivalently 
                (ty3
                    g
                    CHead
                      CHead
                        CHead (CSort O) (Bind Abst) (TSort O)
                        Bind Abst
                        TSort O
                      Bind Abst
                      TLRef O
                    THead
                      Flat Appl
                      TLRef O
                      THead (Bind Abst) (TLRef (S (S O))) (TSort O)
                    u)
                  →∀P:Prop.P
           suppose H: 
              ty3
                g
                CHead
                  CHead
                    CHead (CSort O) (Bind Abst) (TSort O)
                    Bind Abst
                    TSort O
                  Bind Abst
                  TLRef O
                THead
                  Flat Appl
                  TLRef O
                  THead (Bind Abst) (TLRef (S (S O))) (TSort O)
                u
           assume P: Prop
             by (ty3_gen_appl . . . . . H)
             we proved 
                ex3_2
                  T
                  T
                  λu:T
                    .λt:T
                      .pc3
                        CHead
                          CHead
                            CHead (CSort O) (Bind Abst) (TSort O)
                            Bind Abst
                            TSort O
                          Bind Abst
                          TLRef O
                        THead (Flat Appl) (TLRef O) (THead (Bind Abst) u t)
                        u
                  λu:T
                    .λt:T
                      .ty3
                        g
                        CHead
                          CHead
                            CHead (CSort O) (Bind Abst) (TSort O)
                            Bind Abst
                            TSort O
                          Bind Abst
                          TLRef O
                        THead (Bind Abst) (TLRef (S (S O))) (TSort O)
                        THead (Bind Abst) u t
                  λu:T
                    .λ:T
                      .ty3
                        g
                        CHead
                          CHead
                            CHead (CSort O) (Bind Abst) (TSort O)
                            Bind Abst
                            TSort O
                          Bind Abst
                          TLRef O
                        TLRef O
                        u
             we proceed by induction on the previous result to prove P
                case ex3_2_intro : x0:T x1:T :pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (THead (Flat Appl) (TLRef O) (THead (Bind Abst) x0 x1)) u H1:ty3 g (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (THead (Bind Abst) (TLRef (S (S O))) (TSort O)) (THead (Bind Abst) x0 x1) H2:ty3 g (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (TLRef O) x0 ⇒
                   the thesis becomes P
                      by (ty3_gen_lref . . . . H2)
                      we proved 
                         or
                           ex3_3
                             C
                             T
                             T
                             λ:C
                               .λ:T
                                 .λt:T
                                   .pc3
                                     CHead
                                       CHead
                                         CHead (CSort O) (Bind Abst) (TSort O)
                                         Bind Abst
                                         TSort O
                                       Bind Abst
                                       TLRef O
                                     lift (S O) O t
                                     x0
                             λe:C
                               .λu:T
                                 .λ:T
                                   .getl
                                     O
                                     CHead
                                       CHead
                                         CHead (CSort O) (Bind Abst) (TSort O)
                                         Bind Abst
                                         TSort O
                                       Bind Abst
                                       TLRef O
                                     CHead e (Bind Abbr) u
                             λe:C.λu:T.λt:T.ty3 g e u t
                           ex3_3
                             C
                             T
                             T
                             λ:C
                               .λu:T
                                 .λ:T
                                   .pc3
                                     CHead
                                       CHead
                                         CHead (CSort O) (Bind Abst) (TSort O)
                                         Bind Abst
                                         TSort O
                                       Bind Abst
                                       TLRef O
                                     lift (S O) O u
                                     x0
                             λe:C
                               .λu:T
                                 .λ:T
                                   .getl
                                     O
                                     CHead
                                       CHead
                                         CHead (CSort O) (Bind Abst) (TSort O)
                                         Bind Abst
                                         TSort O
                                       Bind Abst
                                       TLRef O
                                     CHead e (Bind Abst) u
                             λe:C.λu:T.λt:T.ty3 g e u t
                      we proceed by induction on the previous result to prove P
                         case or_introl : H3:ex3_3 C T T λ:C.λ:T.λt:T.pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S O) O t) x0 λe:C.λu0:T.λ:T.getl O (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead e (Bind Abbr) u0) λe:C.λu0:T.λt:T.ty3 g e u0 t ⇒
                            the thesis becomes P
                               we proceed by induction on H3 to prove P
                                  case ex3_3_intro : x2:C x3:T x4:T :pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S O) O x4) x0 H5:getl O (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead x2 (Bind Abbr) x3) :ty3 g x2 x3 x4 ⇒
                                     the thesis becomes P
                                        by (ty3_gen_bind . . . . . . H1)
                                        we proved 
                                           ex3_2
                                             T
                                             T
                                             λt2:T
                                               .λ:T
                                                 .pc3
                                                   CHead
                                                     CHead
                                                       CHead (CSort O) (Bind Abst) (TSort O)
                                                       Bind Abst
                                                       TSort O
                                                     Bind Abst
                                                     TLRef O
                                                   THead (Bind Abst) (TLRef (S (S O))) t2
                                                   THead (Bind Abst) x0 x1
                                             λ:T
                                               .λt:T
                                                 .ty3
                                                   g
                                                   CHead
                                                     CHead
                                                       CHead (CSort O) (Bind Abst) (TSort O)
                                                       Bind Abst
                                                       TSort O
                                                     Bind Abst
                                                     TLRef O
                                                   TLRef (S (S O))
                                                   t
                                             λt2:T
                                               .λ:T
                                                 .ty3
                                                   g
                                                   CHead
                                                     CHead
                                                       CHead
                                                         CHead (CSort O) (Bind Abst) (TSort O)
                                                         Bind Abst
                                                         TSort O
                                                       Bind Abst
                                                       TLRef O
                                                     Bind Abst
                                                     TLRef (S (S O))
                                                   TSort O
                                                   t2
                                        we proceed by induction on the previous result to prove P
                                           case ex3_2_intro : x5:T x6:T :pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (THead (Bind Abst) (TLRef (S (S O))) x5) (THead (Bind Abst) x0 x1) H8:ty3 g (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (TLRef (S (S O))) x6 :ty3 g (CHead (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (Bind Abst) (TLRef (S (S O)))) (TSort O) x5 ⇒
                                              the thesis becomes P
                                                 by (ty3_gen_lref . . . . H8)
                                                 we proved 
                                                    or
                                                      ex3_3
                                                        C
                                                        T
                                                        T
                                                        λ:C
                                                          .λ:T
                                                            .λt:T
                                                              .pc3
                                                                CHead
                                                                  CHead
                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                    Bind Abst
                                                                    TSort O
                                                                  Bind Abst
                                                                  TLRef O
                                                                lift (S (S (S O))) O t
                                                                x6
                                                        λe:C
                                                          .λu:T
                                                            .λ:T
                                                              .getl
                                                                S (S O)
                                                                CHead
                                                                  CHead
                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                    Bind Abst
                                                                    TSort O
                                                                  Bind Abst
                                                                  TLRef O
                                                                CHead e (Bind Abbr) u
                                                        λe:C.λu:T.λt:T.ty3 g e u t
                                                      ex3_3
                                                        C
                                                        T
                                                        T
                                                        λ:C
                                                          .λu:T
                                                            .λ:T
                                                              .pc3
                                                                CHead
                                                                  CHead
                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                    Bind Abst
                                                                    TSort O
                                                                  Bind Abst
                                                                  TLRef O
                                                                lift (S (S (S O))) O u
                                                                x6
                                                        λe:C
                                                          .λu:T
                                                            .λ:T
                                                              .getl
                                                                S (S O)
                                                                CHead
                                                                  CHead
                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                    Bind Abst
                                                                    TSort O
                                                                  Bind Abst
                                                                  TLRef O
                                                                CHead e (Bind Abst) u
                                                        λe:C.λu:T.λt:T.ty3 g e u t
                                                 we proceed by induction on the previous result to prove P
                                                    case or_introl : H10:ex3_3 C T T λ:C.λ:T.λt:T.pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S (S (S O))) O t) x6 λe:C.λu0:T.λ:T.getl (S (S O)) (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead e (Bind Abbr) u0) λe:C.λu0:T.λt:T.ty3 g e u0 t ⇒
                                                       the thesis becomes P
                                                          we proceed by induction on H10 to prove P
                                                             case ex3_3_intro : x7:C x8:T x9:T :pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S (S (S O))) O x9) x6 H12:getl (S (S O)) (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead x7 (Bind Abbr) x8) :ty3 g x7 x8 x9 ⇒
                                                                the thesis becomes P
                                                                   (H14) 
                                                                      by (getl_gen_S . . . . . H12)
                                                                      we proved 
                                                                         getl
                                                                           r (Bind Abst) (S O)
                                                                           CHead
                                                                             CHead (CSort O) (Bind Abst) (TSort O)
                                                                             Bind Abst
                                                                             TSort O
                                                                           CHead x7 (Bind Abbr) x8
                                                                      by (getl_gen_all . . . previous)

                                                                         ex2
                                                                           C
                                                                           λe:C
                                                                             .drop
                                                                               r (Bind Abst) (S O)
                                                                               O
                                                                               CHead
                                                                                 CHead (CSort O) (Bind Abst) (TSort O)
                                                                                 Bind Abst
                                                                                 TSort O
                                                                               e
                                                                           λe:C.clear e (CHead x7 (Bind Abbr) x8)
                                                                   end of H14
                                                                   consider H14
                                                                   we proved 
                                                                      ex2
                                                                        C
                                                                        λe:C
                                                                          .drop
                                                                            r (Bind Abst) (S O)
                                                                            O
                                                                            CHead
                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                              Bind Abst
                                                                              TSort O
                                                                            e
                                                                        λe:C.clear e (CHead x7 (Bind Abbr) x8)
                                                                   that is equivalent to 
                                                                      ex2
                                                                        C
                                                                        λe:C
                                                                          .drop
                                                                            S O
                                                                            O
                                                                            CHead
                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                              Bind Abst
                                                                              TSort O
                                                                            e
                                                                        λe:C.clear e (CHead x7 (Bind Abbr) x8)
                                                                   we proceed by induction on the previous result to prove P
                                                                      case ex_intro2 : x:C :drop (S O) O (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) x :clear x (CHead x7 (Bind Abbr) x8) ⇒
                                                                         the thesis becomes P
                                                                            (H17) 
                                                                               by (getl_gen_O . . H5)
                                                                               we proved 
                                                                                  clear
                                                                                    CHead
                                                                                      CHead
                                                                                        CHead (CSort O) (Bind Abst) (TSort O)
                                                                                        Bind Abst
                                                                                        TSort O
                                                                                      Bind Abst
                                                                                      TLRef O
                                                                                    CHead x2 (Bind Abbr) x3
                                                                               by (clear_gen_bind . . . . previous)
                                                                               we proved 
                                                                                  eq
                                                                                    C
                                                                                    CHead x2 (Bind Abbr) x3
                                                                                    CHead
                                                                                      CHead
                                                                                        CHead (CSort O) (Bind Abst) (TSort O)
                                                                                        Bind Abst
                                                                                        TSort O
                                                                                      Bind Abst
                                                                                      TLRef O
                                                                               we proceed by induction on the previous result to prove 
                                                                                  <λ:C.Prop>
                                                                                    CASE CHead
                                                                                            CHead
                                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                                              Bind Abst
                                                                                              TSort O
                                                                                            Bind Abst
                                                                                            TLRef O OF
                                                                                      CSort ⇒False
                                                                                    | CHead  k ⇒
                                                                                          <λ:K.Prop>
                                                                                            CASE k OF
                                                                                              Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                            | Flat ⇒False
                                                                                  case refl_equal : ⇒
                                                                                     the thesis becomes 
                                                                                     <λ:C.Prop>
                                                                                       CASE CHead x2 (Bind Abbr) x3 OF
                                                                                         CSort ⇒False
                                                                                       | CHead  k ⇒
                                                                                             <λ:K.Prop>
                                                                                               CASE k OF
                                                                                                 Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                               | Flat ⇒False
                                                                                        consider I
                                                                                        we proved True

                                                                                           <λ:C.Prop>
                                                                                             CASE CHead x2 (Bind Abbr) x3 OF
                                                                                               CSort ⇒False
                                                                                             | CHead  k ⇒
                                                                                                   <λ:K.Prop>
                                                                                                     CASE k OF
                                                                                                       Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                                     | Flat ⇒False

                                                                                  <λ:C.Prop>
                                                                                    CASE CHead
                                                                                            CHead
                                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                                              Bind Abst
                                                                                              TSort O
                                                                                            Bind Abst
                                                                                            TLRef O OF
                                                                                      CSort ⇒False
                                                                                    | CHead  k ⇒
                                                                                          <λ:K.Prop>
                                                                                            CASE k OF
                                                                                              Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                            | Flat ⇒False
                                                                            end of H17
                                                                            consider H17
                                                                            we proved 
                                                                               <λ:C.Prop>
                                                                                 CASE CHead
                                                                                         CHead
                                                                                           CHead (CSort O) (Bind Abst) (TSort O)
                                                                                           Bind Abst
                                                                                           TSort O
                                                                                         Bind Abst
                                                                                         TLRef O OF
                                                                                   CSort ⇒False
                                                                                 | CHead  k ⇒
                                                                                       <λ:K.Prop>
                                                                                         CASE k OF
                                                                                           Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                         | Flat ⇒False
                                                                            that is equivalent to False
                                                                            we proceed by induction on the previous result to prove P
P
P
P
                                                    case or_intror : H10:ex3_3 C T T λ:C.λu0:T.λ:T.pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S (S (S O))) O u0) x6 λe:C.λu0:T.λ:T.getl (S (S O)) (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead e (Bind Abst) u0) λe:C.λu0:T.λt:T.ty3 g e u0 t ⇒
                                                       the thesis becomes P
                                                          we proceed by induction on H10 to prove P
                                                             case ex3_3_intro : x7:C x8:T x9:T :pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S (S (S O))) O x8) x6 H12:getl (S (S O)) (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead x7 (Bind Abst) x8) :ty3 g x7 x8 x9 ⇒
                                                                the thesis becomes P
                                                                   (H14) 
                                                                      by (getl_gen_S . . . . . H12)
                                                                      we proved 
                                                                         getl
                                                                           r (Bind Abst) (S O)
                                                                           CHead
                                                                             CHead (CSort O) (Bind Abst) (TSort O)
                                                                             Bind Abst
                                                                             TSort O
                                                                           CHead x7 (Bind Abst) x8
                                                                      by (getl_gen_all . . . previous)

                                                                         ex2
                                                                           C
                                                                           λe:C
                                                                             .drop
                                                                               r (Bind Abst) (S O)
                                                                               O
                                                                               CHead
                                                                                 CHead (CSort O) (Bind Abst) (TSort O)
                                                                                 Bind Abst
                                                                                 TSort O
                                                                               e
                                                                           λe:C.clear e (CHead x7 (Bind Abst) x8)
                                                                   end of H14
                                                                   consider H14
                                                                   we proved 
                                                                      ex2
                                                                        C
                                                                        λe:C
                                                                          .drop
                                                                            r (Bind Abst) (S O)
                                                                            O
                                                                            CHead
                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                              Bind Abst
                                                                              TSort O
                                                                            e
                                                                        λe:C.clear e (CHead x7 (Bind Abst) x8)
                                                                   that is equivalent to 
                                                                      ex2
                                                                        C
                                                                        λe:C
                                                                          .drop
                                                                            S O
                                                                            O
                                                                            CHead
                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                              Bind Abst
                                                                              TSort O
                                                                            e
                                                                        λe:C.clear e (CHead x7 (Bind Abst) x8)
                                                                   we proceed by induction on the previous result to prove P
                                                                      case ex_intro2 : x:C :drop (S O) O (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) x :clear x (CHead x7 (Bind Abst) x8) ⇒
                                                                         the thesis becomes P
                                                                            (H17) 
                                                                               by (getl_gen_O . . H5)
                                                                               we proved 
                                                                                  clear
                                                                                    CHead
                                                                                      CHead
                                                                                        CHead (CSort O) (Bind Abst) (TSort O)
                                                                                        Bind Abst
                                                                                        TSort O
                                                                                      Bind Abst
                                                                                      TLRef O
                                                                                    CHead x2 (Bind Abbr) x3
                                                                               by (clear_gen_bind . . . . previous)
                                                                               we proved 
                                                                                  eq
                                                                                    C
                                                                                    CHead x2 (Bind Abbr) x3
                                                                                    CHead
                                                                                      CHead
                                                                                        CHead (CSort O) (Bind Abst) (TSort O)
                                                                                        Bind Abst
                                                                                        TSort O
                                                                                      Bind Abst
                                                                                      TLRef O
                                                                               we proceed by induction on the previous result to prove 
                                                                                  <λ:C.Prop>
                                                                                    CASE CHead
                                                                                            CHead
                                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                                              Bind Abst
                                                                                              TSort O
                                                                                            Bind Abst
                                                                                            TLRef O OF
                                                                                      CSort ⇒False
                                                                                    | CHead  k ⇒
                                                                                          <λ:K.Prop>
                                                                                            CASE k OF
                                                                                              Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                            | Flat ⇒False
                                                                                  case refl_equal : ⇒
                                                                                     the thesis becomes 
                                                                                     <λ:C.Prop>
                                                                                       CASE CHead x2 (Bind Abbr) x3 OF
                                                                                         CSort ⇒False
                                                                                       | CHead  k ⇒
                                                                                             <λ:K.Prop>
                                                                                               CASE k OF
                                                                                                 Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                               | Flat ⇒False
                                                                                        consider I
                                                                                        we proved True

                                                                                           <λ:C.Prop>
                                                                                             CASE CHead x2 (Bind Abbr) x3 OF
                                                                                               CSort ⇒False
                                                                                             | CHead  k ⇒
                                                                                                   <λ:K.Prop>
                                                                                                     CASE k OF
                                                                                                       Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                                     | Flat ⇒False

                                                                                  <λ:C.Prop>
                                                                                    CASE CHead
                                                                                            CHead
                                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                                              Bind Abst
                                                                                              TSort O
                                                                                            Bind Abst
                                                                                            TLRef O OF
                                                                                      CSort ⇒False
                                                                                    | CHead  k ⇒
                                                                                          <λ:K.Prop>
                                                                                            CASE k OF
                                                                                              Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                            | Flat ⇒False
                                                                            end of H17
                                                                            consider H17
                                                                            we proved 
                                                                               <λ:C.Prop>
                                                                                 CASE CHead
                                                                                         CHead
                                                                                           CHead (CSort O) (Bind Abst) (TSort O)
                                                                                           Bind Abst
                                                                                           TSort O
                                                                                         Bind Abst
                                                                                         TLRef O OF
                                                                                   CSort ⇒False
                                                                                 | CHead  k ⇒
                                                                                       <λ:K.Prop>
                                                                                         CASE k OF
                                                                                           Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                         | Flat ⇒False
                                                                            that is equivalent to False
                                                                            we proceed by induction on the previous result to prove P
P
P
P
P
P
P
                         case or_intror : H3:ex3_3 C T T λ:C.λu0:T.λ:T.pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S O) O u0) x0 λe:C.λu0:T.λ:T.getl O (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead e (Bind Abst) u0) λe:C.λu0:T.λt:T.ty3 g e u0 t ⇒
                            the thesis becomes P
                               we proceed by induction on H3 to prove P
                                  case ex3_3_intro : x2:C x3:T x4:T H4:pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S O) O x3) x0 H5:getl O (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead x2 (Bind Abst) x3) H6:ty3 g x2 x3 x4 ⇒
                                     the thesis becomes P
                                        by (ty3_gen_bind . . . . . . H1)
                                        we proved 
                                           ex3_2
                                             T
                                             T
                                             λt2:T
                                               .λ:T
                                                 .pc3
                                                   CHead
                                                     CHead
                                                       CHead (CSort O) (Bind Abst) (TSort O)
                                                       Bind Abst
                                                       TSort O
                                                     Bind Abst
                                                     TLRef O
                                                   THead (Bind Abst) (TLRef (S (S O))) t2
                                                   THead (Bind Abst) x0 x1
                                             λ:T
                                               .λt:T
                                                 .ty3
                                                   g
                                                   CHead
                                                     CHead
                                                       CHead (CSort O) (Bind Abst) (TSort O)
                                                       Bind Abst
                                                       TSort O
                                                     Bind Abst
                                                     TLRef O
                                                   TLRef (S (S O))
                                                   t
                                             λt2:T
                                               .λ:T
                                                 .ty3
                                                   g
                                                   CHead
                                                     CHead
                                                       CHead
                                                         CHead (CSort O) (Bind Abst) (TSort O)
                                                         Bind Abst
                                                         TSort O
                                                       Bind Abst
                                                       TLRef O
                                                     Bind Abst
                                                     TLRef (S (S O))
                                                   TSort O
                                                   t2
                                        we proceed by induction on the previous result to prove P
                                           case ex3_2_intro : x5:T x6:T H7:pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (THead (Bind Abst) (TLRef (S (S O))) x5) (THead (Bind Abst) x0 x1) H8:ty3 g (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (TLRef (S (S O))) x6 :ty3 g (CHead (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (Bind Abst) (TLRef (S (S O)))) (TSort O) x5 ⇒
                                              the thesis becomes P
                                                 by (ty3_gen_lref . . . . H8)
                                                 we proved 
                                                    or
                                                      ex3_3
                                                        C
                                                        T
                                                        T
                                                        λ:C
                                                          .λ:T
                                                            .λt:T
                                                              .pc3
                                                                CHead
                                                                  CHead
                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                    Bind Abst
                                                                    TSort O
                                                                  Bind Abst
                                                                  TLRef O
                                                                lift (S (S (S O))) O t
                                                                x6
                                                        λe:C
                                                          .λu:T
                                                            .λ:T
                                                              .getl
                                                                S (S O)
                                                                CHead
                                                                  CHead
                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                    Bind Abst
                                                                    TSort O
                                                                  Bind Abst
                                                                  TLRef O
                                                                CHead e (Bind Abbr) u
                                                        λe:C.λu:T.λt:T.ty3 g e u t
                                                      ex3_3
                                                        C
                                                        T
                                                        T
                                                        λ:C
                                                          .λu:T
                                                            .λ:T
                                                              .pc3
                                                                CHead
                                                                  CHead
                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                    Bind Abst
                                                                    TSort O
                                                                  Bind Abst
                                                                  TLRef O
                                                                lift (S (S (S O))) O u
                                                                x6
                                                        λe:C
                                                          .λu:T
                                                            .λ:T
                                                              .getl
                                                                S (S O)
                                                                CHead
                                                                  CHead
                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                    Bind Abst
                                                                    TSort O
                                                                  Bind Abst
                                                                  TLRef O
                                                                CHead e (Bind Abst) u
                                                        λe:C.λu:T.λt:T.ty3 g e u t
                                                 we proceed by induction on the previous result to prove P
                                                    case or_introl : H10:ex3_3 C T T λ:C.λ:T.λt:T.pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S (S (S O))) O t) x6 λe:C.λu0:T.λ:T.getl (S (S O)) (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead e (Bind Abbr) u0) λe:C.λu0:T.λt:T.ty3 g e u0 t ⇒
                                                       the thesis becomes P
                                                          we proceed by induction on H10 to prove P
                                                             case ex3_3_intro : x7:C x8:T x9:T :pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S (S (S O))) O x9) x6 H12:getl (S (S O)) (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead x7 (Bind Abbr) x8) :ty3 g x7 x8 x9 ⇒
                                                                the thesis becomes P
                                                                   (H14) 
                                                                      by (getl_gen_S . . . . . H12)
                                                                      we proved 
                                                                         getl
                                                                           r (Bind Abst) (S O)
                                                                           CHead
                                                                             CHead (CSort O) (Bind Abst) (TSort O)
                                                                             Bind Abst
                                                                             TSort O
                                                                           CHead x7 (Bind Abbr) x8
                                                                      by (getl_gen_all . . . previous)

                                                                         ex2
                                                                           C
                                                                           λe:C
                                                                             .drop
                                                                               r (Bind Abst) (S O)
                                                                               O
                                                                               CHead
                                                                                 CHead (CSort O) (Bind Abst) (TSort O)
                                                                                 Bind Abst
                                                                                 TSort O
                                                                               e
                                                                           λe:C.clear e (CHead x7 (Bind Abbr) x8)
                                                                   end of H14
                                                                   consider H14
                                                                   we proved 
                                                                      ex2
                                                                        C
                                                                        λe:C
                                                                          .drop
                                                                            r (Bind Abst) (S O)
                                                                            O
                                                                            CHead
                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                              Bind Abst
                                                                              TSort O
                                                                            e
                                                                        λe:C.clear e (CHead x7 (Bind Abbr) x8)
                                                                   that is equivalent to 
                                                                      ex2
                                                                        C
                                                                        λe:C
                                                                          .drop
                                                                            S O
                                                                            O
                                                                            CHead
                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                              Bind Abst
                                                                              TSort O
                                                                            e
                                                                        λe:C.clear e (CHead x7 (Bind Abbr) x8)
                                                                   we proceed by induction on the previous result to prove P
                                                                      case ex_intro2 : x:C H15:drop (S O) O (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) x H16:clear x (CHead x7 (Bind Abbr) x8) ⇒
                                                                         the thesis becomes P
                                                                            (H17) 
                                                                               by (getl_gen_O . . H5)
                                                                               we proved 
                                                                                  clear
                                                                                    CHead
                                                                                      CHead
                                                                                        CHead (CSort O) (Bind Abst) (TSort O)
                                                                                        Bind Abst
                                                                                        TSort O
                                                                                      Bind Abst
                                                                                      TLRef O
                                                                                    CHead x2 (Bind Abst) x3
                                                                               by (clear_gen_bind . . . . previous)
                                                                               we proved 
                                                                                  eq
                                                                                    C
                                                                                    CHead x2 (Bind Abst) x3
                                                                                    CHead
                                                                                      CHead
                                                                                        CHead (CSort O) (Bind Abst) (TSort O)
                                                                                        Bind Abst
                                                                                        TSort O
                                                                                      Bind Abst
                                                                                      TLRef O
                                                                               by (f_equal . . . . . previous)
                                                                               we proved 
                                                                                  eq
                                                                                    C
                                                                                    <λ:C.C> CASE CHead x2 (Bind Abst) x3 OF CSort ⇒x2 | CHead c  ⇒c
                                                                                    <λ:C.C>
                                                                                      CASE CHead
                                                                                              CHead
                                                                                                CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                Bind Abst
                                                                                                TSort O
                                                                                              Bind Abst
                                                                                              TLRef O OF
                                                                                        CSort ⇒x2
                                                                                      | CHead c  ⇒c

                                                                                  eq
                                                                                    C
                                                                                    λe:C.<λ:C.C> CASE e OF CSort ⇒x2 | CHead c  ⇒c (CHead x2 (Bind Abst) x3)
                                                                                    λe:C.<λ:C.C> CASE e OF CSort ⇒x2 | CHead c  ⇒c
                                                                                      CHead
                                                                                        CHead
                                                                                          CHead (CSort O) (Bind Abst) (TSort O)
                                                                                          Bind Abst
                                                                                          TSort O
                                                                                        Bind Abst
                                                                                        TLRef O
                                                                            end of H17
                                                                            (h1) 
                                                                               (H18) 
                                                                                  by (getl_gen_O . . H5)
                                                                                  we proved 
                                                                                     clear
                                                                                       CHead
                                                                                         CHead
                                                                                           CHead (CSort O) (Bind Abst) (TSort O)
                                                                                           Bind Abst
                                                                                           TSort O
                                                                                         Bind Abst
                                                                                         TLRef O
                                                                                       CHead x2 (Bind Abst) x3
                                                                                  by (clear_gen_bind . . . . previous)
                                                                                  we proved 
                                                                                     eq
                                                                                       C
                                                                                       CHead x2 (Bind Abst) x3
                                                                                       CHead
                                                                                         CHead
                                                                                           CHead (CSort O) (Bind Abst) (TSort O)
                                                                                           Bind Abst
                                                                                           TSort O
                                                                                         Bind Abst
                                                                                         TLRef O
                                                                                  by (f_equal . . . . . previous)
                                                                                  we proved 
                                                                                     eq
                                                                                       T
                                                                                       <λ:C.T> CASE CHead x2 (Bind Abst) x3 OF CSort ⇒x3 | CHead   t⇒t
                                                                                       <λ:C.T>
                                                                                         CASE CHead
                                                                                                 CHead
                                                                                                   CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                   Bind Abst
                                                                                                   TSort O
                                                                                                 Bind Abst
                                                                                                 TLRef O OF
                                                                                           CSort ⇒x3
                                                                                         | CHead   t⇒t

                                                                                     eq
                                                                                       T
                                                                                       λe:C.<λ:C.T> CASE e OF CSort ⇒x3 | CHead   t⇒t (CHead x2 (Bind Abst) x3)
                                                                                       λe:C.<λ:C.T> CASE e OF CSort ⇒x3 | CHead   t⇒t
                                                                                         CHead
                                                                                           CHead
                                                                                             CHead (CSort O) (Bind Abst) (TSort O)
                                                                                             Bind Abst
                                                                                             TSort O
                                                                                           Bind Abst
                                                                                           TLRef O
                                                                               end of H18
                                                                               suppose H19: 
                                                                                  eq
                                                                                    C
                                                                                    x2
                                                                                    CHead
                                                                                      CHead (CSort O) (Bind Abst) (TSort O)
                                                                                      Bind Abst
                                                                                      TSort O
                                                                                  (H20) 
                                                                                     consider H18
                                                                                     we proved 
                                                                                        eq
                                                                                          T
                                                                                          <λ:C.T> CASE CHead x2 (Bind Abst) x3 OF CSort ⇒x3 | CHead   t⇒t
                                                                                          <λ:C.T>
                                                                                            CASE CHead
                                                                                                    CHead
                                                                                                      CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                      Bind Abst
                                                                                                      TSort O
                                                                                                    Bind Abst
                                                                                                    TLRef O OF
                                                                                              CSort ⇒x3
                                                                                            | CHead   t⇒t
                                                                                     that is equivalent to eq T x3 (TLRef O)
                                                                                     we proceed by induction on the previous result to prove ty3 g x2 (TLRef O) x4
                                                                                        case refl_equal : ⇒
                                                                                           the thesis becomes the hypothesis H6
ty3 g x2 (TLRef O) x4
                                                                                  end of H20
                                                                                  (H23) 
                                                                                     by (drop_gen_drop . . . . . H15)
                                                                                     we proved 
                                                                                        drop
                                                                                          r (Bind Abst) O
                                                                                          O
                                                                                          CHead (CSort O) (Bind Abst) (TSort O)
                                                                                          x
                                                                                     that is equivalent to drop O O (CHead (CSort O) (Bind Abst) (TSort O)) x
                                                                                     by (drop_gen_refl . . previous)
                                                                                     we proved eq C (CHead (CSort O) (Bind Abst) (TSort O)) x
                                                                                     by (eq_ind_r . . . H16 . previous)

                                                                                        clear
                                                                                          CHead (CSort O) (Bind Abst) (TSort O)
                                                                                          CHead x7 (Bind Abbr) x8
                                                                                  end of H23
                                                                                  (H24) 
                                                                                     by (clear_gen_bind . . . . H23)
                                                                                     we proved 
                                                                                        eq
                                                                                          C
                                                                                          CHead x7 (Bind Abbr) x8
                                                                                          CHead (CSort O) (Bind Abst) (TSort O)
                                                                                     we proceed by induction on the previous result to prove 
                                                                                        <λ:C.Prop>
                                                                                          CASE CHead (CSort O) (Bind Abst) (TSort O) OF
                                                                                            CSort ⇒False
                                                                                          | CHead  k ⇒
                                                                                                <λ:K.Prop>
                                                                                                  CASE k OF
                                                                                                    Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                                  | Flat ⇒False
                                                                                        case refl_equal : ⇒
                                                                                           the thesis becomes 
                                                                                           <λ:C.Prop>
                                                                                             CASE CHead x7 (Bind Abbr) x8 OF
                                                                                               CSort ⇒False
                                                                                             | CHead  k ⇒
                                                                                                   <λ:K.Prop>
                                                                                                     CASE k OF
                                                                                                       Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                                     | Flat ⇒False
                                                                                              consider I
                                                                                              we proved True

                                                                                                 <λ:C.Prop>
                                                                                                   CASE CHead x7 (Bind Abbr) x8 OF
                                                                                                     CSort ⇒False
                                                                                                   | CHead  k ⇒
                                                                                                         <λ:K.Prop>
                                                                                                           CASE k OF
                                                                                                             Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                                           | Flat ⇒False

                                                                                        <λ:C.Prop>
                                                                                          CASE CHead (CSort O) (Bind Abst) (TSort O) OF
                                                                                            CSort ⇒False
                                                                                          | CHead  k ⇒
                                                                                                <λ:K.Prop>
                                                                                                  CASE k OF
                                                                                                    Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                                  | Flat ⇒False
                                                                                  end of H24
                                                                                  consider H24
                                                                                  we proved 
                                                                                     <λ:C.Prop>
                                                                                       CASE CHead (CSort O) (Bind Abst) (TSort O) OF
                                                                                         CSort ⇒False
                                                                                       | CHead  k ⇒
                                                                                             <λ:K.Prop>
                                                                                               CASE k OF
                                                                                                 Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                               | Flat ⇒False
                                                                                  that is equivalent to False
                                                                                  we proceed by induction on the previous result to prove P
                                                                                  we proved P

                                                                                  (eq
                                                                                      C
                                                                                      x2
                                                                                      CHead
                                                                                        CHead (CSort O) (Bind Abst) (TSort O)
                                                                                        Bind Abst
                                                                                        TSort O)
                                                                                    →P
                                                                            end of h1
                                                                            (h2) 
                                                                               consider H17
                                                                               we proved 
                                                                                  eq
                                                                                    C
                                                                                    <λ:C.C> CASE CHead x2 (Bind Abst) x3 OF CSort ⇒x2 | CHead c  ⇒c
                                                                                    <λ:C.C>
                                                                                      CASE CHead
                                                                                              CHead
                                                                                                CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                Bind Abst
                                                                                                TSort O
                                                                                              Bind Abst
                                                                                              TLRef O OF
                                                                                        CSort ⇒x2
                                                                                      | CHead c  ⇒c

                                                                                  eq
                                                                                    C
                                                                                    x2
                                                                                    CHead
                                                                                      CHead (CSort O) (Bind Abst) (TSort O)
                                                                                      Bind Abst
                                                                                      TSort O
                                                                            end of h2
                                                                            by (h1 h2)
P
P
P
                                                    case or_intror : H10:ex3_3 C T T λ:C.λu0:T.λ:T.pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S (S (S O))) O u0) x6 λe:C.λu0:T.λ:T.getl (S (S O)) (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead e (Bind Abst) u0) λe:C.λu0:T.λt:T.ty3 g e u0 t ⇒
                                                       the thesis becomes P
                                                          we proceed by induction on H10 to prove P
                                                             case ex3_3_intro : x7:C x8:T x9:T H11:pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (lift (S (S (S O))) O x8) x6 H12:getl (S (S O)) (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (CHead x7 (Bind Abst) x8) H13:ty3 g x7 x8 x9 ⇒
                                                                the thesis becomes P
                                                                   (H14) 
                                                                      by (getl_gen_S . . . . . H12)
                                                                      we proved 
                                                                         getl
                                                                           r (Bind Abst) (S O)
                                                                           CHead
                                                                             CHead (CSort O) (Bind Abst) (TSort O)
                                                                             Bind Abst
                                                                             TSort O
                                                                           CHead x7 (Bind Abst) x8
                                                                      by (getl_gen_all . . . previous)

                                                                         ex2
                                                                           C
                                                                           λe:C
                                                                             .drop
                                                                               r (Bind Abst) (S O)
                                                                               O
                                                                               CHead
                                                                                 CHead (CSort O) (Bind Abst) (TSort O)
                                                                                 Bind Abst
                                                                                 TSort O
                                                                               e
                                                                           λe:C.clear e (CHead x7 (Bind Abst) x8)
                                                                   end of H14
                                                                   consider H14
                                                                   we proved 
                                                                      ex2
                                                                        C
                                                                        λe:C
                                                                          .drop
                                                                            r (Bind Abst) (S O)
                                                                            O
                                                                            CHead
                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                              Bind Abst
                                                                              TSort O
                                                                            e
                                                                        λe:C.clear e (CHead x7 (Bind Abst) x8)
                                                                   that is equivalent to 
                                                                      ex2
                                                                        C
                                                                        λe:C
                                                                          .drop
                                                                            S O
                                                                            O
                                                                            CHead
                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                              Bind Abst
                                                                              TSort O
                                                                            e
                                                                        λe:C.clear e (CHead x7 (Bind Abst) x8)
                                                                   we proceed by induction on the previous result to prove P
                                                                      case ex_intro2 : x:C H15:drop (S O) O (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) x H16:clear x (CHead x7 (Bind Abst) x8) ⇒
                                                                         the thesis becomes P
                                                                            (H17) 
                                                                               by (getl_gen_O . . H5)
                                                                               we proved 
                                                                                  clear
                                                                                    CHead
                                                                                      CHead
                                                                                        CHead (CSort O) (Bind Abst) (TSort O)
                                                                                        Bind Abst
                                                                                        TSort O
                                                                                      Bind Abst
                                                                                      TLRef O
                                                                                    CHead x2 (Bind Abst) x3
                                                                               by (clear_gen_bind . . . . previous)
                                                                               we proved 
                                                                                  eq
                                                                                    C
                                                                                    CHead x2 (Bind Abst) x3
                                                                                    CHead
                                                                                      CHead
                                                                                        CHead (CSort O) (Bind Abst) (TSort O)
                                                                                        Bind Abst
                                                                                        TSort O
                                                                                      Bind Abst
                                                                                      TLRef O
                                                                               by (f_equal . . . . . previous)
                                                                               we proved 
                                                                                  eq
                                                                                    C
                                                                                    <λ:C.C> CASE CHead x2 (Bind Abst) x3 OF CSort ⇒x2 | CHead c  ⇒c
                                                                                    <λ:C.C>
                                                                                      CASE CHead
                                                                                              CHead
                                                                                                CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                Bind Abst
                                                                                                TSort O
                                                                                              Bind Abst
                                                                                              TLRef O OF
                                                                                        CSort ⇒x2
                                                                                      | CHead c  ⇒c

                                                                                  eq
                                                                                    C
                                                                                    λe:C.<λ:C.C> CASE e OF CSort ⇒x2 | CHead c  ⇒c (CHead x2 (Bind Abst) x3)
                                                                                    λe:C.<λ:C.C> CASE e OF CSort ⇒x2 | CHead c  ⇒c
                                                                                      CHead
                                                                                        CHead
                                                                                          CHead (CSort O) (Bind Abst) (TSort O)
                                                                                          Bind Abst
                                                                                          TSort O
                                                                                        Bind Abst
                                                                                        TLRef O
                                                                            end of H17
                                                                            (h1) 
                                                                               (H18) 
                                                                                  by (getl_gen_O . . H5)
                                                                                  we proved 
                                                                                     clear
                                                                                       CHead
                                                                                         CHead
                                                                                           CHead (CSort O) (Bind Abst) (TSort O)
                                                                                           Bind Abst
                                                                                           TSort O
                                                                                         Bind Abst
                                                                                         TLRef O
                                                                                       CHead x2 (Bind Abst) x3
                                                                                  by (clear_gen_bind . . . . previous)
                                                                                  we proved 
                                                                                     eq
                                                                                       C
                                                                                       CHead x2 (Bind Abst) x3
                                                                                       CHead
                                                                                         CHead
                                                                                           CHead (CSort O) (Bind Abst) (TSort O)
                                                                                           Bind Abst
                                                                                           TSort O
                                                                                         Bind Abst
                                                                                         TLRef O
                                                                                  by (f_equal . . . . . previous)
                                                                                  we proved 
                                                                                     eq
                                                                                       T
                                                                                       <λ:C.T> CASE CHead x2 (Bind Abst) x3 OF CSort ⇒x3 | CHead   t⇒t
                                                                                       <λ:C.T>
                                                                                         CASE CHead
                                                                                                 CHead
                                                                                                   CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                   Bind Abst
                                                                                                   TSort O
                                                                                                 Bind Abst
                                                                                                 TLRef O OF
                                                                                           CSort ⇒x3
                                                                                         | CHead   t⇒t

                                                                                     eq
                                                                                       T
                                                                                       λe:C.<λ:C.T> CASE e OF CSort ⇒x3 | CHead   t⇒t (CHead x2 (Bind Abst) x3)
                                                                                       λe:C.<λ:C.T> CASE e OF CSort ⇒x3 | CHead   t⇒t
                                                                                         CHead
                                                                                           CHead
                                                                                             CHead (CSort O) (Bind Abst) (TSort O)
                                                                                             Bind Abst
                                                                                             TSort O
                                                                                           Bind Abst
                                                                                           TLRef O
                                                                               end of H18
                                                                               suppose H19: 
                                                                                  eq
                                                                                    C
                                                                                    x2
                                                                                    CHead
                                                                                      CHead (CSort O) (Bind Abst) (TSort O)
                                                                                      Bind Abst
                                                                                      TSort O
                                                                                  (H20) 
                                                                                     consider H18
                                                                                     we proved 
                                                                                        eq
                                                                                          T
                                                                                          <λ:C.T> CASE CHead x2 (Bind Abst) x3 OF CSort ⇒x3 | CHead   t⇒t
                                                                                          <λ:C.T>
                                                                                            CASE CHead
                                                                                                    CHead
                                                                                                      CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                      Bind Abst
                                                                                                      TSort O
                                                                                                    Bind Abst
                                                                                                    TLRef O OF
                                                                                              CSort ⇒x3
                                                                                            | CHead   t⇒t
                                                                                     that is equivalent to eq T x3 (TLRef O)
                                                                                     we proceed by induction on the previous result to prove ty3 g x2 (TLRef O) x4
                                                                                        case refl_equal : ⇒
                                                                                           the thesis becomes the hypothesis H6
ty3 g x2 (TLRef O) x4
                                                                                  end of H20
                                                                                  (H21) 
                                                                                     consider H18
                                                                                     we proved 
                                                                                        eq
                                                                                          T
                                                                                          <λ:C.T> CASE CHead x2 (Bind Abst) x3 OF CSort ⇒x3 | CHead   t⇒t
                                                                                          <λ:C.T>
                                                                                            CASE CHead
                                                                                                    CHead
                                                                                                      CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                      Bind Abst
                                                                                                      TSort O
                                                                                                    Bind Abst
                                                                                                    TLRef O OF
                                                                                              CSort ⇒x3
                                                                                            | CHead   t⇒t
                                                                                     that is equivalent to eq T x3 (TLRef O)
                                                                                     we proceed by induction on the previous result to prove 
                                                                                        pc3
                                                                                          CHead
                                                                                            CHead
                                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                                              Bind Abst
                                                                                              TSort O
                                                                                            Bind Abst
                                                                                            TLRef O
                                                                                          lift (S O) O (TLRef O)
                                                                                          x0
                                                                                        case refl_equal : ⇒
                                                                                           the thesis becomes the hypothesis H4

                                                                                        pc3
                                                                                          CHead
                                                                                            CHead
                                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                                              Bind Abst
                                                                                              TSort O
                                                                                            Bind Abst
                                                                                            TLRef O
                                                                                          lift (S O) O (TLRef O)
                                                                                          x0
                                                                                  end of H21
                                                                                  (H22) 
                                                                                     we proceed by induction on H19 to prove 
                                                                                        ty3
                                                                                          g
                                                                                          CHead
                                                                                            CHead (CSort O) (Bind Abst) (TSort O)
                                                                                            Bind Abst
                                                                                            TSort O
                                                                                          TLRef O
                                                                                          x4
                                                                                        case refl_equal : ⇒
                                                                                           the thesis becomes the hypothesis H20

                                                                                        ty3
                                                                                          g
                                                                                          CHead
                                                                                            CHead (CSort O) (Bind Abst) (TSort O)
                                                                                            Bind Abst
                                                                                            TSort O
                                                                                          TLRef O
                                                                                          x4
                                                                                  end of H22
                                                                                  (H23) 
                                                                                     by (drop_gen_drop . . . . . H15)
                                                                                     we proved 
                                                                                        drop
                                                                                          r (Bind Abst) O
                                                                                          O
                                                                                          CHead (CSort O) (Bind Abst) (TSort O)
                                                                                          x
                                                                                     that is equivalent to drop O O (CHead (CSort O) (Bind Abst) (TSort O)) x
                                                                                     by (drop_gen_refl . . previous)
                                                                                     we proved eq C (CHead (CSort O) (Bind Abst) (TSort O)) x
                                                                                     by (eq_ind_r . . . H16 . previous)

                                                                                        clear
                                                                                          CHead (CSort O) (Bind Abst) (TSort O)
                                                                                          CHead x7 (Bind Abst) x8
                                                                                  end of H23
                                                                                  (H24) 
                                                                                     by (clear_gen_bind . . . . H23)
                                                                                     we proved 
                                                                                        eq
                                                                                          C
                                                                                          CHead x7 (Bind Abst) x8
                                                                                          CHead (CSort O) (Bind Abst) (TSort O)
                                                                                     by (f_equal . . . . . previous)
                                                                                     we proved 
                                                                                        eq
                                                                                          C
                                                                                          <λ:C.C> CASE CHead x7 (Bind Abst) x8 OF CSort ⇒x7 | CHead c  ⇒c
                                                                                          <λ:C.C>
                                                                                            CASE CHead (CSort O) (Bind Abst) (TSort O) OF
                                                                                              CSort ⇒x7
                                                                                            | CHead c  ⇒c

                                                                                        eq
                                                                                          C
                                                                                          λe:C.<λ:C.C> CASE e OF CSort ⇒x7 | CHead c  ⇒c (CHead x7 (Bind Abst) x8)
                                                                                          λe:C.<λ:C.C> CASE e OF CSort ⇒x7 | CHead c  ⇒c
                                                                                            CHead (CSort O) (Bind Abst) (TSort O)
                                                                                  end of H24
                                                                                  (h1) 
                                                                                     (H25) 
                                                                                        by (clear_gen_bind . . . . H23)
                                                                                        we proved 
                                                                                           eq
                                                                                             C
                                                                                             CHead x7 (Bind Abst) x8
                                                                                             CHead (CSort O) (Bind Abst) (TSort O)
                                                                                        by (f_equal . . . . . previous)
                                                                                        we proved 
                                                                                           eq
                                                                                             T
                                                                                             <λ:C.T> CASE CHead x7 (Bind Abst) x8 OF CSort ⇒x8 | CHead   t⇒t
                                                                                             <λ:C.T>
                                                                                               CASE CHead (CSort O) (Bind Abst) (TSort O) OF
                                                                                                 CSort ⇒x8
                                                                                               | CHead   t⇒t

                                                                                           eq
                                                                                             T
                                                                                             λe:C.<λ:C.T> CASE e OF CSort ⇒x8 | CHead   t⇒t (CHead x7 (Bind Abst) x8)
                                                                                             λe:C.<λ:C.T> CASE e OF CSort ⇒x8 | CHead   t⇒t
                                                                                               CHead (CSort O) (Bind Abst) (TSort O)
                                                                                     end of H25
                                                                                     suppose H26: eq C x7 (CSort O)
                                                                                        (H27) 
                                                                                           consider H25
                                                                                           we proved 
                                                                                              eq
                                                                                                T
                                                                                                <λ:C.T> CASE CHead x7 (Bind Abst) x8 OF CSort ⇒x8 | CHead   t⇒t
                                                                                                <λ:C.T>
                                                                                                  CASE CHead (CSort O) (Bind Abst) (TSort O) OF
                                                                                                    CSort ⇒x8
                                                                                                  | CHead   t⇒t
                                                                                           that is equivalent to eq T x8 (TSort O)
                                                                                           we proceed by induction on the previous result to prove ty3 g x7 (TSort O) x9
                                                                                              case refl_equal : ⇒
                                                                                                 the thesis becomes the hypothesis H13
ty3 g x7 (TSort O) x9
                                                                                        end of H27
                                                                                        by (ty3_gen_lref . . . . H22)
                                                                                        we proved 
                                                                                           or
                                                                                             ex3_3
                                                                                               C
                                                                                               T
                                                                                               T
                                                                                               λ:C
                                                                                                 .λ:T
                                                                                                   .λt:T
                                                                                                     .pc3
                                                                                                       CHead
                                                                                                         CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                         Bind Abst
                                                                                                         TSort O
                                                                                                       lift (S O) O t
                                                                                                       x4
                                                                                               λe:C
                                                                                                 .λu:T
                                                                                                   .λ:T
                                                                                                     .getl
                                                                                                       O
                                                                                                       CHead
                                                                                                         CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                         Bind Abst
                                                                                                         TSort O
                                                                                                       CHead e (Bind Abbr) u
                                                                                               λe:C.λu:T.λt:T.ty3 g e u t
                                                                                             ex3_3
                                                                                               C
                                                                                               T
                                                                                               T
                                                                                               λ:C
                                                                                                 .λu:T
                                                                                                   .λ:T
                                                                                                     .pc3
                                                                                                       CHead
                                                                                                         CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                         Bind Abst
                                                                                                         TSort O
                                                                                                       lift (S O) O u
                                                                                                       x4
                                                                                               λe:C
                                                                                                 .λu:T
                                                                                                   .λ:T
                                                                                                     .getl
                                                                                                       O
                                                                                                       CHead
                                                                                                         CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                         Bind Abst
                                                                                                         TSort O
                                                                                                       CHead e (Bind Abst) u
                                                                                               λe:C.λu:T.λt:T.ty3 g e u t
                                                                                        we proceed by induction on the previous result to prove P
                                                                                           case or_introl : H30:ex3_3 C T T λ:C.λ:T.λt:T.pc3 (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (lift (S O) O t) x4 λe:C.λu0:T.λ:T.getl O (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (CHead e (Bind Abbr) u0) λe:C.λu0:T.λt:T.ty3 g e u0 t ⇒
                                                                                              the thesis becomes P
                                                                                                 we proceed by induction on H30 to prove P
                                                                                                    case ex3_3_intro : x10:C x11:T x12:T :pc3 (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (lift (S O) O x12) x4 H32:getl O (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (CHead x10 (Bind Abbr) x11) :ty3 g x10 x11 x12 ⇒
                                                                                                       the thesis becomes P
                                                                                                          (H34) 
                                                                                                             by (getl_gen_O . . H32)
                                                                                                             we proved 
                                                                                                                clear
                                                                                                                  CHead
                                                                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                    Bind Abst
                                                                                                                    TSort O
                                                                                                                  CHead x10 (Bind Abbr) x11
                                                                                                             by (clear_gen_bind . . . . previous)
                                                                                                             we proved 
                                                                                                                eq
                                                                                                                  C
                                                                                                                  CHead x10 (Bind Abbr) x11
                                                                                                                  CHead
                                                                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                    Bind Abst
                                                                                                                    TSort O
                                                                                                             we proceed by induction on the previous result to prove 
                                                                                                                <λ:C.Prop>
                                                                                                                  CASE CHead
                                                                                                                          CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                          Bind Abst
                                                                                                                          TSort O OF
                                                                                                                    CSort ⇒False
                                                                                                                  | CHead  k ⇒
                                                                                                                        <λ:K.Prop>
                                                                                                                          CASE k OF
                                                                                                                            Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                                                          | Flat ⇒False
                                                                                                                case refl_equal : ⇒
                                                                                                                   the thesis becomes 
                                                                                                                   <λ:C.Prop>
                                                                                                                     CASE CHead x10 (Bind Abbr) x11 OF
                                                                                                                       CSort ⇒False
                                                                                                                     | CHead  k ⇒
                                                                                                                           <λ:K.Prop>
                                                                                                                             CASE k OF
                                                                                                                               Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                                                             | Flat ⇒False
                                                                                                                      consider I
                                                                                                                      we proved True

                                                                                                                         <λ:C.Prop>
                                                                                                                           CASE CHead x10 (Bind Abbr) x11 OF
                                                                                                                             CSort ⇒False
                                                                                                                           | CHead  k ⇒
                                                                                                                                 <λ:K.Prop>
                                                                                                                                   CASE k OF
                                                                                                                                     Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                                                                   | Flat ⇒False

                                                                                                                <λ:C.Prop>
                                                                                                                  CASE CHead
                                                                                                                          CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                          Bind Abst
                                                                                                                          TSort O OF
                                                                                                                    CSort ⇒False
                                                                                                                  | CHead  k ⇒
                                                                                                                        <λ:K.Prop>
                                                                                                                          CASE k OF
                                                                                                                            Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                                                          | Flat ⇒False
                                                                                                          end of H34
                                                                                                          consider H34
                                                                                                          we proved 
                                                                                                             <λ:C.Prop>
                                                                                                               CASE CHead
                                                                                                                       CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                       Bind Abst
                                                                                                                       TSort O OF
                                                                                                                 CSort ⇒False
                                                                                                               | CHead  k ⇒
                                                                                                                     <λ:K.Prop>
                                                                                                                       CASE k OF
                                                                                                                         Bind b⇒<λ:B.Prop> CASE b OF Abbr⇒True | Abst⇒False | Void⇒False
                                                                                                                       | Flat ⇒False
                                                                                                          that is equivalent to False
                                                                                                          we proceed by induction on the previous result to prove P
P
P
                                                                                           case or_intror : H30:ex3_3 C T T λ:C.λu0:T.λ:T.pc3 (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (lift (S O) O u0) x4 λe:C.λu0:T.λ:T.getl O (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (CHead e (Bind Abst) u0) λe:C.λu0:T.λt:T.ty3 g e u0 t ⇒
                                                                                              the thesis becomes P
                                                                                                 we proceed by induction on H30 to prove P
                                                                                                    case ex3_3_intro : x10:C x11:T x12:T H31:pc3 (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (lift (S O) O x11) x4 H32:getl O (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (CHead x10 (Bind Abst) x11) H33:ty3 g x10 x11 x12 ⇒
                                                                                                       the thesis becomes P
                                                                                                          (H34) 
                                                                                                             by (getl_gen_O . . H32)
                                                                                                             we proved 
                                                                                                                clear
                                                                                                                  CHead
                                                                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                    Bind Abst
                                                                                                                    TSort O
                                                                                                                  CHead x10 (Bind Abst) x11
                                                                                                             by (clear_gen_bind . . . . previous)
                                                                                                             we proved 
                                                                                                                eq
                                                                                                                  C
                                                                                                                  CHead x10 (Bind Abst) x11
                                                                                                                  CHead
                                                                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                    Bind Abst
                                                                                                                    TSort O
                                                                                                             by (f_equal . . . . . previous)
                                                                                                             we proved 
                                                                                                                eq
                                                                                                                  C
                                                                                                                  <λ:C.C> CASE CHead x10 (Bind Abst) x11 OF CSort ⇒x10 | CHead c  ⇒c
                                                                                                                  <λ:C.C>
                                                                                                                    CASE CHead
                                                                                                                            CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                            Bind Abst
                                                                                                                            TSort O OF
                                                                                                                      CSort ⇒x10
                                                                                                                    | CHead c  ⇒c

                                                                                                                eq
                                                                                                                  C
                                                                                                                  λe:C.<λ:C.C> CASE e OF CSort ⇒x10 | CHead c  ⇒c (CHead x10 (Bind Abst) x11)
                                                                                                                  λe:C.<λ:C.C> CASE e OF CSort ⇒x10 | CHead c  ⇒c
                                                                                                                    CHead
                                                                                                                      CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                      Bind Abst
                                                                                                                      TSort O
                                                                                                          end of H34
                                                                                                          (h1) 
                                                                                                             (H35) 
                                                                                                                by (getl_gen_O . . H32)
                                                                                                                we proved 
                                                                                                                   clear
                                                                                                                     CHead
                                                                                                                       CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                       Bind Abst
                                                                                                                       TSort O
                                                                                                                     CHead x10 (Bind Abst) x11
                                                                                                                by (clear_gen_bind . . . . previous)
                                                                                                                we proved 
                                                                                                                   eq
                                                                                                                     C
                                                                                                                     CHead x10 (Bind Abst) x11
                                                                                                                     CHead
                                                                                                                       CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                       Bind Abst
                                                                                                                       TSort O
                                                                                                                by (f_equal . . . . . previous)
                                                                                                                we proved 
                                                                                                                   eq
                                                                                                                     T
                                                                                                                     <λ:C.T> CASE CHead x10 (Bind Abst) x11 OF CSort ⇒x11 | CHead   t⇒t
                                                                                                                     <λ:C.T>
                                                                                                                       CASE CHead
                                                                                                                               CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                               Bind Abst
                                                                                                                               TSort O OF
                                                                                                                         CSort ⇒x11
                                                                                                                       | CHead   t⇒t

                                                                                                                   eq
                                                                                                                     T
                                                                                                                     λe:C.<λ:C.T> CASE e OF CSort ⇒x11 | CHead   t⇒t (CHead x10 (Bind Abst) x11)
                                                                                                                     λe:C.<λ:C.T> CASE e OF CSort ⇒x11 | CHead   t⇒t
                                                                                                                       CHead
                                                                                                                         CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                         Bind Abst
                                                                                                                         TSort O
                                                                                                             end of H35
                                                                                                             suppose H36: eq C x10 (CHead (CSort O) (Bind Abst) (TSort O))
                                                                                                                (H37) 
                                                                                                                   consider H35
                                                                                                                   we proved 
                                                                                                                      eq
                                                                                                                        T
                                                                                                                        <λ:C.T> CASE CHead x10 (Bind Abst) x11 OF CSort ⇒x11 | CHead   t⇒t
                                                                                                                        <λ:C.T>
                                                                                                                          CASE CHead
                                                                                                                                  CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                  Bind Abst
                                                                                                                                  TSort O OF
                                                                                                                            CSort ⇒x11
                                                                                                                          | CHead   t⇒t
                                                                                                                   that is equivalent to eq T x11 (TSort O)
                                                                                                                   we proceed by induction on the previous result to prove ty3 g x10 (TSort O) x12
                                                                                                                      case refl_equal : ⇒
                                                                                                                         the thesis becomes the hypothesis H33
ty3 g x10 (TSort O) x12
                                                                                                                end of H37
                                                                                                                by (pc3_gen_abst . . . . . H7)
                                                                                                                we proved 
                                                                                                                   land
                                                                                                                     pc3
                                                                                                                       CHead
                                                                                                                         CHead
                                                                                                                           CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                           Bind Abst
                                                                                                                           TSort O
                                                                                                                         Bind Abst
                                                                                                                         TLRef O
                                                                                                                       TLRef (S (S O))
                                                                                                                       x0
                                                                                                                     ∀b:B
                                                                                                                       .∀u:T
                                                                                                                         .pc3
                                                                                                                           CHead
                                                                                                                             CHead
                                                                                                                               CHead
                                                                                                                                 CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                 Bind Abst
                                                                                                                                 TSort O
                                                                                                                               Bind Abst
                                                                                                                               TLRef O
                                                                                                                             Bind b
                                                                                                                             u
                                                                                                                           x5
                                                                                                                           x1
                                                                                                                we proceed by induction on the previous result to prove P
                                                                                                                   case conj : H40:pc3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (TLRef (S (S O))) x0 :∀b:B.∀u0:T.(pc3 (CHead (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (Bind b) u0) x5 x1) ⇒
                                                                                                                      the thesis becomes P
                                                                                                                         (H42) 
                                                                                                                            by (le_n .)
                                                                                                                            we proved le O O
                                                                                                                            by (lift_lref_ge . . . previous)
                                                                                                                            we proved eq T (lift (S O) O (TLRef O)) (TLRef (plus O (S O)))
                                                                                                                            we proceed by induction on the previous result to prove 
                                                                                                                               pc3
                                                                                                                                 CHead
                                                                                                                                   CHead
                                                                                                                                     CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                     Bind Abst
                                                                                                                                     TSort O
                                                                                                                                   Bind Abst
                                                                                                                                   TLRef O
                                                                                                                                 TLRef (S (S O))
                                                                                                                                 TLRef (plus O (S O))
                                                                                                                               case refl_equal : ⇒
                                                                                                                                  the thesis becomes 
                                                                                                                                  pc3
                                                                                                                                    CHead
                                                                                                                                      CHead
                                                                                                                                        CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                        Bind Abst
                                                                                                                                        TSort O
                                                                                                                                      Bind Abst
                                                                                                                                      TLRef O
                                                                                                                                    TLRef (S (S O))
                                                                                                                                    lift (S O) O (TLRef O)
                                                                                                                                     consider H21
                                                                                                                                     we proved 
                                                                                                                                        pc3
                                                                                                                                          CHead
                                                                                                                                            CHead
                                                                                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                              Bind Abst
                                                                                                                                              TSort O
                                                                                                                                            Bind Abst
                                                                                                                                            TLRef O
                                                                                                                                          lift (S O) O (TLRef O)
                                                                                                                                          x0
                                                                                                                                     that is equivalent to 
                                                                                                                                        ex2
                                                                                                                                          T
                                                                                                                                          λx:T
                                                                                                                                            .pr3
                                                                                                                                              CHead
                                                                                                                                                CHead
                                                                                                                                                  CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                  Bind Abst
                                                                                                                                                  TSort O
                                                                                                                                                Bind Abst
                                                                                                                                                TLRef O
                                                                                                                                              lift (S O) O (TLRef O)
                                                                                                                                              x
                                                                                                                                          λx:T
                                                                                                                                            .pr3
                                                                                                                                              CHead
                                                                                                                                                CHead
                                                                                                                                                  CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                  Bind Abst
                                                                                                                                                  TSort O
                                                                                                                                                Bind Abst
                                                                                                                                                TLRef O
                                                                                                                                              x0
                                                                                                                                              x
                                                                                                                                     by (ex2_sym . . . previous)
                                                                                                                                     we proved 
                                                                                                                                        ex2
                                                                                                                                          T
                                                                                                                                          λx:T
                                                                                                                                            .pr3
                                                                                                                                              CHead
                                                                                                                                                CHead
                                                                                                                                                  CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                  Bind Abst
                                                                                                                                                  TSort O
                                                                                                                                                Bind Abst
                                                                                                                                                TLRef O
                                                                                                                                              x0
                                                                                                                                              x
                                                                                                                                          λx:T
                                                                                                                                            .pr3
                                                                                                                                              CHead
                                                                                                                                                CHead
                                                                                                                                                  CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                  Bind Abst
                                                                                                                                                  TSort O
                                                                                                                                                Bind Abst
                                                                                                                                                TLRef O
                                                                                                                                              lift (S O) O (TLRef O)
                                                                                                                                              x
                                                                                                                                     that is equivalent to 
                                                                                                                                        pc3
                                                                                                                                          CHead
                                                                                                                                            CHead
                                                                                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                              Bind Abst
                                                                                                                                              TSort O
                                                                                                                                            Bind Abst
                                                                                                                                            TLRef O
                                                                                                                                          x0
                                                                                                                                          lift (S O) O (TLRef O)
                                                                                                                                     by (pc3_t . . . H40 . previous)

                                                                                                                                        pc3
                                                                                                                                          CHead
                                                                                                                                            CHead
                                                                                                                                              CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                              Bind Abst
                                                                                                                                              TSort O
                                                                                                                                            Bind Abst
                                                                                                                                            TLRef O
                                                                                                                                          TLRef (S (S O))
                                                                                                                                          lift (S O) O (TLRef O)

                                                                                                                               pc3
                                                                                                                                 CHead
                                                                                                                                   CHead
                                                                                                                                     CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                     Bind Abst
                                                                                                                                     TSort O
                                                                                                                                   Bind Abst
                                                                                                                                   TLRef O
                                                                                                                                 TLRef (S (S O))
                                                                                                                                 TLRef (plus O (S O))
                                                                                                                         end of H42
                                                                                                                         (H43) consider H42
                                                                                                                         consider H43
                                                                                                                         we proved 
                                                                                                                            pc3
                                                                                                                              CHead
                                                                                                                                CHead
                                                                                                                                  CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                  Bind Abst
                                                                                                                                  TSort O
                                                                                                                                Bind Abst
                                                                                                                                TLRef O
                                                                                                                              TLRef (S (S O))
                                                                                                                              TLRef (plus O (S O))
                                                                                                                         that is equivalent to 
                                                                                                                            ex2
                                                                                                                              T
                                                                                                                              λt:T
                                                                                                                                .pr3
                                                                                                                                  CHead
                                                                                                                                    CHead
                                                                                                                                      CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                      Bind Abst
                                                                                                                                      TSort O
                                                                                                                                    Bind Abst
                                                                                                                                    TLRef O
                                                                                                                                  TLRef (S (S O))
                                                                                                                                  t
                                                                                                                              λt:T
                                                                                                                                .pr3
                                                                                                                                  CHead
                                                                                                                                    CHead
                                                                                                                                      CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                      Bind Abst
                                                                                                                                      TSort O
                                                                                                                                    Bind Abst
                                                                                                                                    TLRef O
                                                                                                                                  TLRef (S O)
                                                                                                                                  t
                                                                                                                         we proceed by induction on the previous result to prove P
                                                                                                                            case ex_intro2 : x13:T H44:pr3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (TLRef (S (S O))) x13 H45:pr3 (CHead (CHead (CHead (CSort O) (Bind Abst) (TSort O)) (Bind Abst) (TSort O)) (Bind Abst) (TLRef O)) (TLRef (S O)) x13 ⇒
                                                                                                                               the thesis becomes P
                                                                                                                                  (H46) 
                                                                                                                                     (h1) 
                                                                                                                                        (h1) 
                                                                                                                                           by (clear_bind . . .)

                                                                                                                                              clear
                                                                                                                                                CHead
                                                                                                                                                  CHead
                                                                                                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                    Bind Abst
                                                                                                                                                    TSort O
                                                                                                                                                  Bind Abst
                                                                                                                                                  TLRef O
                                                                                                                                                CHead
                                                                                                                                                  CHead
                                                                                                                                                    CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                    Bind Abst
                                                                                                                                                    TSort O
                                                                                                                                                  Bind Abst
                                                                                                                                                  TLRef O
                                                                                                                                        end of h1
                                                                                                                                        (h2) 
                                                                                                                                           by (getl_refl . . .)
                                                                                                                                           we proved 
                                                                                                                                              getl
                                                                                                                                                O
                                                                                                                                                CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                           that is equivalent to 
                                                                                                                                              getl
                                                                                                                                                r (Bind Abst) O
                                                                                                                                                CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                           by (getl_head . . . . previous .)

                                                                                                                                              getl
                                                                                                                                                S O
                                                                                                                                                CHead
                                                                                                                                                  CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                  Bind Abst
                                                                                                                                                  TSort O
                                                                                                                                                CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                        end of h2
                                                                                                                                        by (getl_clear_bind . . . . h1 . . h2)
                                                                                                                                        we proved 
                                                                                                                                           getl
                                                                                                                                             S (S O)
                                                                                                                                             CHead
                                                                                                                                               CHead
                                                                                                                                                 CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                 Bind Abst
                                                                                                                                                 TSort O
                                                                                                                                               Bind Abst
                                                                                                                                               TLRef O
                                                                                                                                             CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                        by (nf2_lref_abst . . . . previous)
                                                                                                                                        we proved 
                                                                                                                                           nf2
                                                                                                                                             CHead
                                                                                                                                               CHead
                                                                                                                                                 CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                 Bind Abst
                                                                                                                                                 TSort O
                                                                                                                                               Bind Abst
                                                                                                                                               TLRef O
                                                                                                                                             TLRef (S (S O))
                                                                                                                                        by (nf2_pr3_unfold . . . H44 previous)
eq T (TLRef (S (S O))) x13
                                                                                                                                     end of h1
                                                                                                                                     (h2) 
                                                                                                                                        by (getl_refl . . .)
                                                                                                                                        we proved 
                                                                                                                                           getl
                                                                                                                                             O
                                                                                                                                             CHead
                                                                                                                                               CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                               Bind Abst
                                                                                                                                               TSort O
                                                                                                                                             CHead
                                                                                                                                               CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                               Bind Abst
                                                                                                                                               TSort O
                                                                                                                                        that is equivalent to 
                                                                                                                                           getl
                                                                                                                                             r (Bind Abst) O
                                                                                                                                             CHead
                                                                                                                                               CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                               Bind Abst
                                                                                                                                               TSort O
                                                                                                                                             CHead
                                                                                                                                               CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                               Bind Abst
                                                                                                                                               TSort O
                                                                                                                                        by (getl_head . . . . previous .)
                                                                                                                                        we proved 
                                                                                                                                           getl
                                                                                                                                             S O
                                                                                                                                             CHead
                                                                                                                                               CHead
                                                                                                                                                 CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                 Bind Abst
                                                                                                                                                 TSort O
                                                                                                                                               Bind Abst
                                                                                                                                               TLRef O
                                                                                                                                             CHead
                                                                                                                                               CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                               Bind Abst
                                                                                                                                               TSort O
                                                                                                                                        by (nf2_lref_abst . . . . previous)
                                                                                                                                        we proved 
                                                                                                                                           nf2
                                                                                                                                             CHead
                                                                                                                                               CHead
                                                                                                                                                 CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                                                 Bind Abst
                                                                                                                                                 TSort O
                                                                                                                                               Bind Abst
                                                                                                                                               TLRef O
                                                                                                                                             TLRef (S O)
                                                                                                                                        by (nf2_pr3_unfold . . . H45 previous)
eq T (TLRef (S O)) x13
                                                                                                                                     end of h2
                                                                                                                                     by (eq_ind_r . . . h1 . h2)
eq T (TLRef (S (S O))) (TLRef (S O))
                                                                                                                                  end of H46
                                                                                                                                  (H47) 
                                                                                                                                     we proceed by induction on H46 to prove 
                                                                                                                                        <λ:T.Prop>
                                                                                                                                          CASE TLRef (S O) OF
                                                                                                                                            TSort ⇒False
                                                                                                                                          | TLRef n⇒<λ:nat.Prop> CASE n OF O⇒False | S n0⇒<λ:nat.Prop> CASE n0 OF O⇒False | S ⇒True
                                                                                                                                          | THead   ⇒False
                                                                                                                                        case refl_equal : ⇒
                                                                                                                                           the thesis becomes 
                                                                                                                                           <λ:T.Prop>
                                                                                                                                             CASE TLRef (S (S O)) OF
                                                                                                                                               TSort ⇒False
                                                                                                                                             | TLRef n⇒<λ:nat.Prop> CASE n OF O⇒False | S n0⇒<λ:nat.Prop> CASE n0 OF O⇒False | S ⇒True
                                                                                                                                             | THead   ⇒False
                                                                                                                                              consider I
                                                                                                                                              we proved True

                                                                                                                                                 <λ:T.Prop>
                                                                                                                                                   CASE TLRef (S (S O)) OF
                                                                                                                                                     TSort ⇒False
                                                                                                                                                   | TLRef n⇒<λ:nat.Prop> CASE n OF O⇒False | S n0⇒<λ:nat.Prop> CASE n0 OF O⇒False | S ⇒True
                                                                                                                                                   | THead   ⇒False

                                                                                                                                        <λ:T.Prop>
                                                                                                                                          CASE TLRef (S O) OF
                                                                                                                                            TSort ⇒False
                                                                                                                                          | TLRef n⇒<λ:nat.Prop> CASE n OF O⇒False | S n0⇒<λ:nat.Prop> CASE n0 OF O⇒False | S ⇒True
                                                                                                                                          | THead   ⇒False
                                                                                                                                  end of H47
                                                                                                                                  consider H47
                                                                                                                                  we proved 
                                                                                                                                     <λ:T.Prop>
                                                                                                                                       CASE TLRef (S O) OF
                                                                                                                                         TSort ⇒False
                                                                                                                                       | TLRef n⇒<λ:nat.Prop> CASE n OF O⇒False | S n0⇒<λ:nat.Prop> CASE n0 OF O⇒False | S ⇒True
                                                                                                                                       | THead   ⇒False
                                                                                                                                  that is equivalent to False
                                                                                                                                  we proceed by induction on the previous result to prove P
P
P
                                                                                                                we proved P
(eq C x10 (CHead (CSort O) (Bind Abst) (TSort O)))→P
                                                                                                          end of h1
                                                                                                          (h2) 
                                                                                                             consider H34
                                                                                                             we proved 
                                                                                                                eq
                                                                                                                  C
                                                                                                                  <λ:C.C> CASE CHead x10 (Bind Abst) x11 OF CSort ⇒x10 | CHead c  ⇒c
                                                                                                                  <λ:C.C>
                                                                                                                    CASE CHead
                                                                                                                            CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                                            Bind Abst
                                                                                                                            TSort O OF
                                                                                                                      CSort ⇒x10
                                                                                                                    | CHead c  ⇒c
eq C x10 (CHead (CSort O) (Bind Abst) (TSort O))
                                                                                                          end of h2
                                                                                                          by (h1 h2)
P
P
                                                                                        we proved P
(eq C x7 (CSort O))→P
                                                                                  end of h1
                                                                                  (h2) 
                                                                                     consider H24
                                                                                     we proved 
                                                                                        eq
                                                                                          C
                                                                                          <λ:C.C> CASE CHead x7 (Bind Abst) x8 OF CSort ⇒x7 | CHead c  ⇒c
                                                                                          <λ:C.C>
                                                                                            CASE CHead (CSort O) (Bind Abst) (TSort O) OF
                                                                                              CSort ⇒x7
                                                                                            | CHead c  ⇒c
eq C x7 (CSort O)
                                                                                  end of h2
                                                                                  by (h1 h2)
                                                                                  we proved P

                                                                                  (eq
                                                                                      C
                                                                                      x2
                                                                                      CHead
                                                                                        CHead (CSort O) (Bind Abst) (TSort O)
                                                                                        Bind Abst
                                                                                        TSort O)
                                                                                    →P
                                                                            end of h1
                                                                            (h2) 
                                                                               consider H17
                                                                               we proved 
                                                                                  eq
                                                                                    C
                                                                                    <λ:C.C> CASE CHead x2 (Bind Abst) x3 OF CSort ⇒x2 | CHead c  ⇒c
                                                                                    <λ:C.C>
                                                                                      CASE CHead
                                                                                              CHead
                                                                                                CHead (CSort O) (Bind Abst) (TSort O)
                                                                                                Bind Abst
                                                                                                TSort O
                                                                                              Bind Abst
                                                                                              TLRef O OF
                                                                                        CSort ⇒x2
                                                                                      | CHead c  ⇒c

                                                                                  eq
                                                                                    C
                                                                                    x2
                                                                                    CHead
                                                                                      CHead (CSort O) (Bind Abst) (TSort O)
                                                                                      Bind Abst
                                                                                      TSort O
                                                                            end of h2
                                                                            by (h1 h2)
P
P
P
P
P
P
P
             we proved P
          we proved 
             (ty3
                 g
                 CHead
                   CHead
                     CHead (CSort O) (Bind Abst) (TSort O)
                     Bind Abst
                     TSort O
                   Bind Abst
                   TLRef O
                 THead
                   Flat Appl
                   TLRef O
                   THead (Bind Abst) (TLRef (S (S O))) (TSort O)
                 u)
               →∀P:Prop.P
          that is equivalent to (ty3 g ex1_c ex1_t u)→∀P:Prop.P
       we proved ∀g:G.∀u:T.(ty3 g ex1_c ex1_t u)→∀P:Prop.P