DEFINITION pr0_gen_void()
TYPE =
       u1:T
         .t1:T
           .x:T
             .pr0 (THead (Bind Void) u1 t1) x
               (or
                    ex3_2 T T λu2:T.λt2:T.eq T x (THead (Bind Void) u2 t2) λu2:T.λ:T.pr0 u1 u2 λ:T.λt2:T.pr0 t1 t2
                    pr0 t1 (lift (S OO x))
BODY =
        assume u1T
        assume t1T
        assume xT
        suppose Hpr0 (THead (Bind Void) u1 t1) x
           assume yT
           suppose H0pr0 y x
             we proceed by induction on H0 to prove 
                eq T y (THead (Bind Void) u1 t1)
                  (or
                       ex3_2 T T λu2:T.λt2:T.eq T x (THead (Bind Void) u2 t2) λu2:T.λ:T.pr0 u1 u2 λ:T.λt2:T.pr0 t1 t2
                       pr0 t1 (lift (S OO x))
                case pr0_refl : t:T 
                   the thesis becomes 
                   H1:eq T t (THead (Bind Void) u1 t1)
                     .or
                       ex3_2 T T λu2:T.λt2:T.eq T t (THead (Bind Void) u2 t2) λu2:T.λ:T.pr0 u1 u2 λ:T.λt2:T.pr0 t1 t2
                       pr0 t1 (lift (S OO t)
                      suppose H1eq T t (THead (Bind Void) u1 t1)
                         (H2
                            by (f_equal . . . . . H1)
                            we proved eq T t (THead (Bind Void) u1 t1)
eq T (λe:T.e t) (λe:T.e (THead (Bind Void) u1 t1))
                         end of H2
                         (h1
                            by (refl_equal . .)
eq T (THead (Bind Void) u1 t1) (THead (Bind Void) u1 t1)
                         end of h1
                         (h2by (pr0_refl .) we proved pr0 u1 u1
                         (h3by (pr0_refl .) we proved pr0 t1 t1
                         by (ex3_2_intro . . . . . . . h1 h2 h3)
                         we proved 
                            ex3_2
                              T
                              T
                              λu2:T.λt2:T.eq T (THead (Bind Void) u1 t1) (THead (Bind Void) u2 t2)
                              λu2:T.λ:T.pr0 u1 u2
                              λ:T.λt2:T.pr0 t1 t2
                         by (or_introl . . previous)
                         we proved 
                            or
                              ex3_2
                                T
                                T
                                λu2:T.λt2:T.eq T (THead (Bind Void) u1 t1) (THead (Bind Void) u2 t2)
                                λu2:T.λ:T.pr0 u1 u2
                                λ:T.λt2:T.pr0 t1 t2
                              pr0 t1 (lift (S OO (THead (Bind Void) u1 t1))
                         by (eq_ind_r . . . previous . H2)
                         we proved 
                            or
                              ex3_2 T T λu2:T.λt2:T.eq T t (THead (Bind Void) u2 t2) λu2:T.λ:T.pr0 u1 u2 λ:T.λt2:T.pr0 t1 t2
                              pr0 t1 (lift (S OO t)

                         H1:eq T t (THead (Bind Void) u1 t1)
                           .or
                             ex3_2 T T λu2:T.λt2:T.eq T t (THead (Bind Void) u2 t2) λu2:T.λ:T.pr0 u1 u2 λ:T.λt2:T.pr0 t1 t2
                             pr0 t1 (lift (S OO t)
                case pr0_comp : u0:T u2:T H1:pr0 u0 u2 t0:T t2:T H3:pr0 t0 t2 k:K 
                   the thesis becomes 
                   H5:eq T (THead k u0 t0) (THead (Bind Void) u1 t1)
                     .or
                       ex3_2 T T λu3:T.λt3:T.eq T (THead k u2 t2) (THead (Bind Void) u3 t3) λu3:T.λ:T.pr0 u1 u3 λ:T.λt3:T.pr0 t1 t3
                       pr0 t1 (lift (S OO (THead k u2 t2))
                   (H2) by induction hypothesis we know 
                      eq T u0 (THead (Bind Void) u1 t1)
                        (or
                             ex3_2 T T λu3:T.λt2:T.eq T u2 (THead (Bind Void) u3 t2) λu3:T.λ:T.pr0 u1 u3 λ:T.λt2:T.pr0 t1 t2
                             pr0 t1 (lift (S OO u2))
                   (H4) by induction hypothesis we know 
                      eq T t0 (THead (Bind Void) u1 t1)
                        (or
                             ex3_2 T T λu3:T.λt3:T.eq T t2 (THead (Bind Void) u3 t3) λu3:T.λ:T.pr0 u1 u3 λ:T.λt3:T.pr0 t1 t3
                             pr0 t1 (lift (S OO t2))
                      suppose H5eq T (THead k u0 t0) (THead (Bind Void) u1 t1)
                         (H6
                            by (f_equal . . . . . H5)
                            we proved 
                               eq
                                 K
                                 <λ:T.K> CASE THead k u0 t0 OF TSort k | TLRef k | THead k0  k0
                                 <λ:T.K> CASE THead (Bind Void) u1 t1 OF TSort k | TLRef k | THead k0  k0

                               eq
                                 K
                                 λe:T.<λ:T.K> CASE e OF TSort k | TLRef k | THead k0  k0 (THead k u0 t0)
                                 λe:T.<λ:T.K> CASE e OF TSort k | TLRef k | THead k0  k0
                                   THead (Bind Void) u1 t1
                         end of H6
                         (h1
                            (H7
                               by (f_equal . . . . . H5)
                               we proved 
                                  eq
                                    T
                                    <λ:T.T> CASE THead k u0 t0 OF TSort u0 | TLRef u0 | THead  t t
                                    <λ:T.T> CASE THead (Bind Void) u1 t1 OF TSort u0 | TLRef u0 | THead  t t

                                  eq
                                    T
                                    λe:T.<λ:T.T> CASE e OF TSort u0 | TLRef u0 | THead  t t (THead k u0 t0)
                                    λe:T.<λ:T.T> CASE e OF TSort u0 | TLRef u0 | THead  t t
                                      THead (Bind Void) u1 t1
                            end of H7
                            (h1
                               (H8
                                  by (f_equal . . . . . H5)
                                  we proved 
                                     eq
                                       T
                                       <λ:T.T> CASE THead k u0 t0 OF TSort t0 | TLRef t0 | THead   tt
                                       <λ:T.T> CASE THead (Bind Void) u1 t1 OF TSort t0 | TLRef t0 | THead   tt

                                     eq
                                       T
                                       λe:T.<λ:T.T> CASE e OF TSort t0 | TLRef t0 | THead   tt (THead k u0 t0)
                                       λe:T.<λ:T.T> CASE e OF TSort t0 | TLRef t0 | THead   tt
                                         THead (Bind Void) u1 t1
                               end of H8
                                suppose H9eq T u0 u1
                                suppose H10eq K k (Bind Void)
                                  (H12
                                     consider H8
                                     we proved 
                                        eq
                                          T
                                          <λ:T.T> CASE THead k u0 t0 OF TSort t0 | TLRef t0 | THead   tt
                                          <λ:T.T> CASE THead (Bind Void) u1 t1 OF TSort t0 | TLRef t0 | THead   tt
                                     that is equivalent to eq T t0 t1
                                     we proceed by induction on the previous result to prove pr0 t1 t2
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H3
pr0 t1 t2
                                  end of H12
                                  (H14
                                     we proceed by induction on H9 to prove pr0 u1 u2
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H1
pr0 u1 u2
                                  end of H14
                                  by (refl_equal . .)
                                  we proved eq T (THead (Bind Void) u2 t2) (THead (Bind Void) u2 t2)
                                  by (ex3_2_intro . . . . . . . previous H14 H12)
                                  we proved 
                                     ex3_2
                                       T
                                       T
                                       λu3:T.λt3:T.eq T (THead (Bind Void) u2 t2) (THead (Bind Void) u3 t3)
                                       λu3:T.λ:T.pr0 u1 u3
                                       λ:T.λt3:T.pr0 t1 t3
                                  by (or_introl . . previous)
                                  we proved 
                                     or
                                       ex3_2
                                         T
                                         T
                                         λu3:T.λt3:T.eq T (THead (Bind Void) u2 t2) (THead (Bind Void) u3 t3)
                                         λu3:T.λ:T.pr0 u1 u3
                                         λ:T.λt3:T.pr0 t1 t3
                                       pr0 t1 (lift (S OO (THead (Bind Void) u2 t2))
                                  by (eq_ind_r . . . previous . H10)
                                  we proved 
                                     or
                                       ex3_2 T T λu3:T.λt3:T.eq T (THead k u2 t2) (THead (Bind Void) u3 t3) λu3:T.λ:T.pr0 u1 u3 λ:T.λt3:T.pr0 t1 t3
                                       pr0 t1 (lift (S OO (THead k u2 t2))

                                  eq T u0 u1
                                    (eq K k (Bind Void)
                                         (or
                                              ex3_2 T T λu3:T.λt3:T.eq T (THead k u2 t2) (THead (Bind Void) u3 t3) λu3:T.λ:T.pr0 u1 u3 λ:T.λt3:T.pr0 t1 t3
                                              pr0 t1 (lift (S OO (THead k u2 t2))))
                            end of h1
                            (h2
                               consider H7
                               we proved 
                                  eq
                                    T
                                    <λ:T.T> CASE THead k u0 t0 OF TSort u0 | TLRef u0 | THead  t t
                                    <λ:T.T> CASE THead (Bind Void) u1 t1 OF TSort u0 | TLRef u0 | THead  t t
eq T u0 u1
                            end of h2
                            by (h1 h2)

                               eq K k (Bind Void)
                                 (or
                                      ex3_2 T T λu3:T.λt3:T.eq T (THead k u2 t2) (THead (Bind Void) u3 t3) λu3:T.λ:T.pr0 u1 u3 λ:T.λt3:T.pr0 t1 t3
                                      pr0 t1 (lift (S OO (THead k u2 t2)))
                         end of h1
                         (h2
                            consider H6
                            we proved 
                               eq
                                 K
                                 <λ:T.K> CASE THead k u0 t0 OF TSort k | TLRef k | THead k0  k0
                                 <λ:T.K> CASE THead (Bind Void) u1 t1 OF TSort k | TLRef k | THead k0  k0
eq K k (Bind Void)
                         end of h2
                         by (h1 h2)
                         we proved 
                            or
                              ex3_2 T T λu3:T.λt3:T.eq T (THead k u2 t2) (THead (Bind Void) u3 t3) λu3:T.λ:T.pr0 u1 u3 λ:T.λt3:T.pr0 t1 t3
                              pr0 t1 (lift (S OO (THead k u2 t2))

                         H5:eq T (THead k u0 t0) (THead (Bind Void) u1 t1)
                           .or
                             ex3_2 T T λu3:T.λt3:T.eq T (THead k u2 t2) (THead (Bind Void) u3 t3) λu3:T.λ:T.pr0 u1 u3 λ:T.λt3:T.pr0 t1 t3
                             pr0 t1 (lift (S OO (THead k u2 t2))
                case pr0_beta : u:T v1:T v2:T :pr0 v1 v2 t0:T t2:T :pr0 t0 t2 
                   the thesis becomes 
                   H5:eq
                              T
                              THead (Flat Appl) v1 (THead (Bind Abst) u t0)
                              THead (Bind Void) u1 t1
                     .or
                       ex3_2
                         T
                         T
                         λu2:T.λt3:T.eq T (THead (Bind Abbr) v2 t2) (THead (Bind Void) u2 t3)
                         λu2:T.λ:T.pr0 u1 u2
                         λ:T.λt3:T.pr0 t1 t3
                       pr0 t1 (lift (S OO (THead (Bind Abbr) v2 t2))
                   () by induction hypothesis we know 
                      eq T v1 (THead (Bind Void) u1 t1)
                        (or
                             ex3_2 T T λu2:T.λt2:T.eq T v2 (THead (Bind Void) u2 t2) λu2:T.λ:T.pr0 u1 u2 λ:T.λt2:T.pr0 t1 t2
                             pr0 t1 (lift (S OO v2))
                   () by induction hypothesis we know 
                      eq T t0 (THead (Bind Void) u1 t1)
                        (or
                             ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                             pr0 t1 (lift (S OO t2))
                      suppose H5
                         eq
                           T
                           THead (Flat Appl) v1 (THead (Bind Abst) u t0)
                           THead (Bind Void) u1 t1
                         (H6
                            we proceed by induction on H5 to prove 
                               <λ:T.Prop>
                                 CASE THead (Bind Void) u1 t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                               case refl_equal : 
                                  the thesis becomes 
                                  <λ:T.Prop>
                                    CASE THead (Flat Appl) v1 (THead (Bind Abst) u t0) OF
                                      TSort False
                                    | TLRef False
                                    | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE THead (Flat Appl) v1 (THead (Bind Abst) u t0) OF
                                            TSort False
                                          | TLRef False
                                          | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True

                               <λ:T.Prop>
                                 CASE THead (Bind Void) u1 t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                         end of H6
                         consider H6
                         we proved 
                            <λ:T.Prop>
                              CASE THead (Bind Void) u1 t1 OF
                                TSort False
                              | TLRef False
                              | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                         that is equivalent to False
                         we proceed by induction on the previous result to prove 
                            or
                              ex3_2
                                T
                                T
                                λu2:T.λt3:T.eq T (THead (Bind Abbr) v2 t2) (THead (Bind Void) u2 t3)
                                λu2:T.λ:T.pr0 u1 u2
                                λ:T.λt3:T.pr0 t1 t3
                              pr0 t1 (lift (S OO (THead (Bind Abbr) v2 t2))
                         we proved 
                            or
                              ex3_2
                                T
                                T
                                λu2:T.λt3:T.eq T (THead (Bind Abbr) v2 t2) (THead (Bind Void) u2 t3)
                                λu2:T.λ:T.pr0 u1 u2
                                λ:T.λt3:T.pr0 t1 t3
                              pr0 t1 (lift (S OO (THead (Bind Abbr) v2 t2))

                         H5:eq
                                    T
                                    THead (Flat Appl) v1 (THead (Bind Abst) u t0)
                                    THead (Bind Void) u1 t1
                           .or
                             ex3_2
                               T
                               T
                               λu2:T.λt3:T.eq T (THead (Bind Abbr) v2 t2) (THead (Bind Void) u2 t3)
                               λu2:T.λ:T.pr0 u1 u2
                               λ:T.λt3:T.pr0 t1 t3
                             pr0 t1 (lift (S OO (THead (Bind Abbr) v2 t2))
                case pr0_upsilon : b:B :not (eq B b Abst) v1:T v2:T :pr0 v1 v2 u0:T u2:T :pr0 u0 u2 t0:T t2:T :pr0 t0 t2 
                   the thesis becomes 
                   H8:eq
                              T
                              THead (Flat Appl) v1 (THead (Bind b) u0 t0)
                              THead (Bind Void) u1 t1
                     .or
                       ex3_2
                         T
                         T
                         λu3:T
                           .λt3:T
                             .eq
                               T
                               THead (Bind b) u2 (THead (Flat Appl) (lift (S OO v2) t2)
                               THead (Bind Void) u3 t3
                         λu3:T.λ:T.pr0 u1 u3
                         λ:T.λt3:T.pr0 t1 t3
                       pr0
                         t1
                         lift
                           S O
                           O
                           THead (Bind b) u2 (THead (Flat Appl) (lift (S OO v2) t2)
                   () by induction hypothesis we know 
                      eq T v1 (THead (Bind Void) u1 t1)
                        (or
                             ex3_2 T T λu2:T.λt2:T.eq T v2 (THead (Bind Void) u2 t2) λu2:T.λ:T.pr0 u1 u2 λ:T.λt2:T.pr0 t1 t2
                             pr0 t1 (lift (S OO v2))
                   () by induction hypothesis we know 
                      eq T u0 (THead (Bind Void) u1 t1)
                        (or
                             ex3_2 T T λu3:T.λt2:T.eq T u2 (THead (Bind Void) u3 t2) λu3:T.λ:T.pr0 u1 u3 λ:T.λt2:T.pr0 t1 t2
                             pr0 t1 (lift (S OO u2))
                   () by induction hypothesis we know 
                      eq T t0 (THead (Bind Void) u1 t1)
                        (or
                             ex3_2 T T λu3:T.λt3:T.eq T t2 (THead (Bind Void) u3 t3) λu3:T.λ:T.pr0 u1 u3 λ:T.λt3:T.pr0 t1 t3
                             pr0 t1 (lift (S OO t2))
                      suppose H8
                         eq
                           T
                           THead (Flat Appl) v1 (THead (Bind b) u0 t0)
                           THead (Bind Void) u1 t1
                         (H9
                            we proceed by induction on H8 to prove 
                               <λ:T.Prop>
                                 CASE THead (Bind Void) u1 t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                               case refl_equal : 
                                  the thesis becomes 
                                  <λ:T.Prop>
                                    CASE THead (Flat Appl) v1 (THead (Bind b) u0 t0) OF
                                      TSort False
                                    | TLRef False
                                    | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE THead (Flat Appl) v1 (THead (Bind b) u0 t0) OF
                                            TSort False
                                          | TLRef False
                                          | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True

                               <λ:T.Prop>
                                 CASE THead (Bind Void) u1 t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                         end of H9
                         consider H9
                         we proved 
                            <λ:T.Prop>
                              CASE THead (Bind Void) u1 t1 OF
                                TSort False
                              | TLRef False
                              | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                         that is equivalent to False
                         we proceed by induction on the previous result to prove 
                            or
                              ex3_2
                                T
                                T
                                λu3:T
                                  .λt3:T
                                    .eq
                                      T
                                      THead (Bind b) u2 (THead (Flat Appl) (lift (S OO v2) t2)
                                      THead (Bind Void) u3 t3
                                λu3:T.λ:T.pr0 u1 u3
                                λ:T.λt3:T.pr0 t1 t3
                              pr0
                                t1
                                lift
                                  S O
                                  O
                                  THead (Bind b) u2 (THead (Flat Appl) (lift (S OO v2) t2)
                         we proved 
                            or
                              ex3_2
                                T
                                T
                                λu3:T
                                  .λt3:T
                                    .eq
                                      T
                                      THead (Bind b) u2 (THead (Flat Appl) (lift (S OO v2) t2)
                                      THead (Bind Void) u3 t3
                                λu3:T.λ:T.pr0 u1 u3
                                λ:T.λt3:T.pr0 t1 t3
                              pr0
                                t1
                                lift
                                  S O
                                  O
                                  THead (Bind b) u2 (THead (Flat Appl) (lift (S OO v2) t2)

                         H8:eq
                                    T
                                    THead (Flat Appl) v1 (THead (Bind b) u0 t0)
                                    THead (Bind Void) u1 t1
                           .or
                             ex3_2
                               T
                               T
                               λu3:T
                                 .λt3:T
                                   .eq
                                     T
                                     THead (Bind b) u2 (THead (Flat Appl) (lift (S OO v2) t2)
                                     THead (Bind Void) u3 t3
                               λu3:T.λ:T.pr0 u1 u3
                               λ:T.λt3:T.pr0 t1 t3
                             pr0
                               t1
                               lift
                                 S O
                                 O
                                 THead (Bind b) u2 (THead (Flat Appl) (lift (S OO v2) t2)
                case pr0_delta : u0:T u2:T :pr0 u0 u2 t0:T t2:T :pr0 t0 t2 w:T :subst0 O u2 t2 w 
                   the thesis becomes 
                   H6:eq T (THead (Bind Abbr) u0 t0) (THead (Bind Void) u1 t1)
                     .or
                       ex3_2
                         T
                         T
                         λu3:T.λt3:T.eq T (THead (Bind Abbr) u2 w) (THead (Bind Void) u3 t3)
                         λu3:T.λ:T.pr0 u1 u3
                         λ:T.λt3:T.pr0 t1 t3
                       pr0 t1 (lift (S OO (THead (Bind Abbr) u2 w))
                   () by induction hypothesis we know 
                      eq T u0 (THead (Bind Void) u1 t1)
                        (or
                             ex3_2 T T λu3:T.λt2:T.eq T u2 (THead (Bind Void) u3 t2) λu3:T.λ:T.pr0 u1 u3 λ:T.λt2:T.pr0 t1 t2
                             pr0 t1 (lift (S OO u2))
                   () by induction hypothesis we know 
                      eq T t0 (THead (Bind Void) u1 t1)
                        (or
                             ex3_2 T T λu3:T.λt3:T.eq T t2 (THead (Bind Void) u3 t3) λu3:T.λ:T.pr0 u1 u3 λ:T.λt3:T.pr0 t1 t3
                             pr0 t1 (lift (S OO t2))
                      suppose H6eq T (THead (Bind Abbr) u0 t0) (THead (Bind Void) u1 t1)
                         (H7
                            we proceed by induction on H6 to prove 
                               <λ:T.Prop>
                                 CASE THead (Bind Void) u1 t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  
                                       <λ:K.Prop>
                                         CASE k OF
                                           Bind b<λ:B.Prop> CASE b OF AbbrTrue | AbstFalse | VoidFalse
                                         | Flat False
                               case refl_equal : 
                                  the thesis becomes 
                                  <λ:T.Prop>
                                    CASE THead (Bind Abbr) u0 t0 OF
                                      TSort False
                                    | TLRef False
                                    | THead k  
                                          <λ:K.Prop>
                                            CASE k OF
                                              Bind b<λ:B.Prop> CASE b OF AbbrTrue | AbstFalse | VoidFalse
                                            | Flat False
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE THead (Bind Abbr) u0 t0 OF
                                            TSort False
                                          | TLRef False
                                          | THead k  
                                                <λ:K.Prop>
                                                  CASE k OF
                                                    Bind b<λ:B.Prop> CASE b OF AbbrTrue | AbstFalse | VoidFalse
                                                  | Flat False

                               <λ:T.Prop>
                                 CASE THead (Bind Void) u1 t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  
                                       <λ:K.Prop>
                                         CASE k OF
                                           Bind b<λ:B.Prop> CASE b OF AbbrTrue | AbstFalse | VoidFalse
                                         | Flat False
                         end of H7
                         consider H7
                         we proved 
                            <λ:T.Prop>
                              CASE THead (Bind Void) u1 t1 OF
                                TSort False
                              | TLRef False
                              | THead k  
                                    <λ:K.Prop>
                                      CASE k OF
                                        Bind b<λ:B.Prop> CASE b OF AbbrTrue | AbstFalse | VoidFalse
                                      | Flat False
                         that is equivalent to False
                         we proceed by induction on the previous result to prove 
                            or
                              ex3_2
                                T
                                T
                                λu3:T.λt3:T.eq T (THead (Bind Abbr) u2 w) (THead (Bind Void) u3 t3)
                                λu3:T.λ:T.pr0 u1 u3
                                λ:T.λt3:T.pr0 t1 t3
                              pr0 t1 (lift (S OO (THead (Bind Abbr) u2 w))
                         we proved 
                            or
                              ex3_2
                                T
                                T
                                λu3:T.λt3:T.eq T (THead (Bind Abbr) u2 w) (THead (Bind Void) u3 t3)
                                λu3:T.λ:T.pr0 u1 u3
                                λ:T.λt3:T.pr0 t1 t3
                              pr0 t1 (lift (S OO (THead (Bind Abbr) u2 w))

                         H6:eq T (THead (Bind Abbr) u0 t0) (THead (Bind Void) u1 t1)
                           .or
                             ex3_2
                               T
                               T
                               λu3:T.λt3:T.eq T (THead (Bind Abbr) u2 w) (THead (Bind Void) u3 t3)
                               λu3:T.λ:T.pr0 u1 u3
                               λ:T.λt3:T.pr0 t1 t3
                             pr0 t1 (lift (S OO (THead (Bind Abbr) u2 w))
                case pr0_zeta : b:B H1:not (eq B b Abst) t0:T t2:T H2:pr0 t0 t2 u:T 
                   the thesis becomes 
                   H4:eq T (THead (Bind b) u (lift (S OO t0)) (THead (Bind Void) u1 t1)
                     .or
                       ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                       pr0 t1 (lift (S OO t2)
                   (H3) by induction hypothesis we know 
                      eq T t0 (THead (Bind Void) u1 t1)
                        (or
                             ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                             pr0 t1 (lift (S OO t2))
                      suppose H4
                         eq T (THead (Bind b) u (lift (S OO t0)) (THead (Bind Void) u1 t1)
                         (H5
                            by (f_equal . . . . . H4)
                            we proved 
                               eq
                                 B
                                 <λ:T.B>
                                   CASE THead (Bind b) u (lift (S OO t0) OF
                                     TSort b
                                   | TLRef b
                                   | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat b
                                 <λ:T.B>
                                   CASE THead (Bind Void) u1 t1 OF
                                     TSort b
                                   | TLRef b
                                   | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat b

                               eq
                                 B
                                 λe:T
                                     .<λ:T.B>
                                       CASE e OF
                                         TSort b
                                       | TLRef b
                                       | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat b
                                   THead (Bind b) u (lift (S OO t0)
                                 λe:T
                                     .<λ:T.B>
                                       CASE e OF
                                         TSort b
                                       | TLRef b
                                       | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat b
                                   THead (Bind Void) u1 t1
                         end of H5
                         (h1
                            (H6
                               by (f_equal . . . . . H4)
                               we proved 
                                  eq
                                    T
                                    <λ:T.T>
                                      CASE THead (Bind b) u (lift (S OO t0) OF
                                        TSort u
                                      | TLRef u
                                      | THead  t t
                                    <λ:T.T>
                                      CASE THead (Bind Void) u1 t1 OF
                                        TSort u
                                      | TLRef u
                                      | THead  t t

                                  eq
                                    T
                                    λe:T.<λ:T.T> CASE e OF TSort u | TLRef u | THead  t t
                                      THead (Bind b) u (lift (S OO t0)
                                    λe:T.<λ:T.T> CASE e OF TSort u | TLRef u | THead  t t
                                      THead (Bind Void) u1 t1
                            end of H6
                            (h1
                               (H7
                                  by (f_equal . . . . . H4)
                                  we proved 
                                     eq
                                       T
                                       <λ:T.T>
                                         CASE THead (Bind b) u (lift (S OO t0) OF
                                           TSort 
                                               FIXlref_map{
                                                   lref_map:(natnat)natTT
                                                   :=λf:natnat
                                                     .λd:nat
                                                       .λt:T
                                                         .<λt3:T.T>
                                                           CASE t OF
                                                             TSort nTSort n
                                                           | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                           | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                   }
                                                 λx0:nat.plus x0 (S O)
                                                 O
                                                 t0
                                         | TLRef 
                                               FIXlref_map{
                                                   lref_map:(natnat)natTT
                                                   :=λf:natnat
                                                     .λd:nat
                                                       .λt:T
                                                         .<λt3:T.T>
                                                           CASE t OF
                                                             TSort nTSort n
                                                           | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                           | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                   }
                                                 λx0:nat.plus x0 (S O)
                                                 O
                                                 t0
                                         | THead   tt
                                       <λ:T.T>
                                         CASE THead (Bind Void) u1 t1 OF
                                           TSort 
                                               FIXlref_map{
                                                   lref_map:(natnat)natTT
                                                   :=λf:natnat
                                                     .λd:nat
                                                       .λt:T
                                                         .<λt3:T.T>
                                                           CASE t OF
                                                             TSort nTSort n
                                                           | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                           | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                   }
                                                 λx0:nat.plus x0 (S O)
                                                 O
                                                 t0
                                         | TLRef 
                                               FIXlref_map{
                                                   lref_map:(natnat)natTT
                                                   :=λf:natnat
                                                     .λd:nat
                                                       .λt:T
                                                         .<λt3:T.T>
                                                           CASE t OF
                                                             TSort nTSort n
                                                           | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                           | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                   }
                                                 λx0:nat.plus x0 (S O)
                                                 O
                                                 t0
                                         | THead   tt

                                     eq
                                       T
                                       λe:T
                                           .<λ:T.T>
                                             CASE e OF
                                               TSort 
                                                   FIXlref_map{
                                                       lref_map:(natnat)natTT
                                                       :=λf:natnat
                                                         .λd:nat
                                                           .λt:T
                                                             .<λt3:T.T>
                                                               CASE t OF
                                                                 TSort nTSort n
                                                               | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                               | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                       }
                                                     λx0:nat.plus x0 (S O)
                                                     O
                                                     t0
                                             | TLRef 
                                                   FIXlref_map{
                                                       lref_map:(natnat)natTT
                                                       :=λf:natnat
                                                         .λd:nat
                                                           .λt:T
                                                             .<λt3:T.T>
                                                               CASE t OF
                                                                 TSort nTSort n
                                                               | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                               | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                       }
                                                     λx0:nat.plus x0 (S O)
                                                     O
                                                     t0
                                             | THead   tt
                                         THead (Bind b) u (lift (S OO t0)
                                       λe:T
                                           .<λ:T.T>
                                             CASE e OF
                                               TSort 
                                                   FIXlref_map{
                                                       lref_map:(natnat)natTT
                                                       :=λf:natnat
                                                         .λd:nat
                                                           .λt:T
                                                             .<λt3:T.T>
                                                               CASE t OF
                                                                 TSort nTSort n
                                                               | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                               | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                       }
                                                     λx0:nat.plus x0 (S O)
                                                     O
                                                     t0
                                             | TLRef 
                                                   FIXlref_map{
                                                       lref_map:(natnat)natTT
                                                       :=λf:natnat
                                                         .λd:nat
                                                           .λt:T
                                                             .<λt3:T.T>
                                                               CASE t OF
                                                                 TSort nTSort n
                                                               | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                               | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                       }
                                                     λx0:nat.plus x0 (S O)
                                                     O
                                                     t0
                                             | THead   tt
                                         THead (Bind Void) u1 t1
                               end of H7
                                suppose eq T u u1
                                suppose H9eq B b Void
                                  consider H7
                                  we proved 
                                     eq
                                       T
                                       <λ:T.T>
                                         CASE THead (Bind b) u (lift (S OO t0) OF
                                           TSort 
                                               FIXlref_map{
                                                   lref_map:(natnat)natTT
                                                   :=λf:natnat
                                                     .λd:nat
                                                       .λt:T
                                                         .<λt3:T.T>
                                                           CASE t OF
                                                             TSort nTSort n
                                                           | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                           | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                   }
                                                 λx0:nat.plus x0 (S O)
                                                 O
                                                 t0
                                         | TLRef 
                                               FIXlref_map{
                                                   lref_map:(natnat)natTT
                                                   :=λf:natnat
                                                     .λd:nat
                                                       .λt:T
                                                         .<λt3:T.T>
                                                           CASE t OF
                                                             TSort nTSort n
                                                           | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                           | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                   }
                                                 λx0:nat.plus x0 (S O)
                                                 O
                                                 t0
                                         | THead   tt
                                       <λ:T.T>
                                         CASE THead (Bind Void) u1 t1 OF
                                           TSort 
                                               FIXlref_map{
                                                   lref_map:(natnat)natTT
                                                   :=λf:natnat
                                                     .λd:nat
                                                       .λt:T
                                                         .<λt3:T.T>
                                                           CASE t OF
                                                             TSort nTSort n
                                                           | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                           | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                   }
                                                 λx0:nat.plus x0 (S O)
                                                 O
                                                 t0
                                         | TLRef 
                                               FIXlref_map{
                                                   lref_map:(natnat)natTT
                                                   :=λf:natnat
                                                     .λd:nat
                                                       .λt:T
                                                         .<λt3:T.T>
                                                           CASE t OF
                                                             TSort nTSort n
                                                           | TLRef iTLRef <λb1:bool.nat> CASE blt i d OF truei | falsef i
                                                           | THead k u0 t3THead k (lref_map f d u0) (lref_map f (s k d) t3)
                                                   }
                                                 λx0:nat.plus x0 (S O)
                                                 O
                                                 t0
                                         | THead   tt
                                  that is equivalent to eq T (lift (S OO t0) t1
                                  we proceed by induction on the previous result to prove 
                                     or
                                       ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                                       pr0 t1 (lift (S OO t2)
                                     case refl_equal : 
                                        the thesis becomes 
                                        or
                                          ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 (lift (S OO t0) t3
                                          pr0 (lift (S OO t0) (lift (S OO t2)
                                           by (pr0_lift . . H2 . .)
                                           we proved pr0 (lift (S OO t0) (lift (S OO t2)
                                           by (or_intror . . previous)

                                              or
                                                ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 (lift (S OO t0) t3
                                                pr0 (lift (S OO t0) (lift (S OO t2)
                                  we proved 
                                     or
                                       ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                                       pr0 t1 (lift (S OO t2)

                                  eq T u u1
                                    (eq B b Void
                                         (or
                                              ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                                              pr0 t1 (lift (S OO t2)))
                            end of h1
                            (h2
                               consider H6
                               we proved 
                                  eq
                                    T
                                    <λ:T.T>
                                      CASE THead (Bind b) u (lift (S OO t0) OF
                                        TSort u
                                      | TLRef u
                                      | THead  t t
                                    <λ:T.T>
                                      CASE THead (Bind Void) u1 t1 OF
                                        TSort u
                                      | TLRef u
                                      | THead  t t
eq T u u1
                            end of h2
                            by (h1 h2)

                               eq B b Void
                                 (or
                                      ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                                      pr0 t1 (lift (S OO t2))
                         end of h1
                         (h2
                            consider H5
                            we proved 
                               eq
                                 B
                                 <λ:T.B>
                                   CASE THead (Bind b) u (lift (S OO t0) OF
                                     TSort b
                                   | TLRef b
                                   | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat b
                                 <λ:T.B>
                                   CASE THead (Bind Void) u1 t1 OF
                                     TSort b
                                   | TLRef b
                                   | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat b
eq B b Void
                         end of h2
                         by (h1 h2)
                         we proved 
                            or
                              ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                              pr0 t1 (lift (S OO t2)

                         H4:eq T (THead (Bind b) u (lift (S OO t0)) (THead (Bind Void) u1 t1)
                           .or
                             ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                             pr0 t1 (lift (S OO t2)
                case pr0_tau : t0:T t2:T :pr0 t0 t2 u:T 
                   the thesis becomes 
                   H3:eq T (THead (Flat Cast) u t0) (THead (Bind Void) u1 t1)
                     .or
                       ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                       pr0 t1 (lift (S OO t2)
                   () by induction hypothesis we know 
                      eq T t0 (THead (Bind Void) u1 t1)
                        (or
                             ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                             pr0 t1 (lift (S OO t2))
                      suppose H3eq T (THead (Flat Cast) u t0) (THead (Bind Void) u1 t1)
                         (H4
                            we proceed by induction on H3 to prove 
                               <λ:T.Prop>
                                 CASE THead (Bind Void) u1 t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                               case refl_equal : 
                                  the thesis becomes 
                                  <λ:T.Prop>
                                    CASE THead (Flat Cast) u t0 OF
                                      TSort False
                                    | TLRef False
                                    | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE THead (Flat Cast) u t0 OF
                                            TSort False
                                          | TLRef False
                                          | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True

                               <λ:T.Prop>
                                 CASE THead (Bind Void) u1 t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                         end of H4
                         consider H4
                         we proved 
                            <λ:T.Prop>
                              CASE THead (Bind Void) u1 t1 OF
                                TSort False
                              | TLRef False
                              | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                         that is equivalent to False
                         we proceed by induction on the previous result to prove 
                            or
                              ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                              pr0 t1 (lift (S OO t2)
                         we proved 
                            or
                              ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                              pr0 t1 (lift (S OO t2)

                         H3:eq T (THead (Flat Cast) u t0) (THead (Bind Void) u1 t1)
                           .or
                             ex3_2 T T λu2:T.λt3:T.eq T t2 (THead (Bind Void) u2 t3) λu2:T.λ:T.pr0 u1 u2 λ:T.λt3:T.pr0 t1 t3
                             pr0 t1 (lift (S OO t2)
             we proved 
                eq T y (THead (Bind Void) u1 t1)
                  (or
                       ex3_2 T T λu2:T.λt2:T.eq T x (THead (Bind Void) u2 t2) λu2:T.λ:T.pr0 u1 u2 λ:T.λt2:T.pr0 t1 t2
                       pr0 t1 (lift (S OO x))
          we proved 
             y:T
               .pr0 y x
                 (eq T y (THead (Bind Void) u1 t1)
                      (or
                           ex3_2 T T λu2:T.λt2:T.eq T x (THead (Bind Void) u2 t2) λu2:T.λ:T.pr0 u1 u2 λ:T.λt2:T.pr0 t1 t2
                           pr0 t1 (lift (S OO x)))
          by (insert_eq . . . . previous H)
          we proved 
             or
               ex3_2 T T λu2:T.λt2:T.eq T x (THead (Bind Void) u2 t2) λu2:T.λ:T.pr0 u1 u2 λ:T.λt2:T.pr0 t1 t2
               pr0 t1 (lift (S OO x)
       we proved 
          u1:T
            .t1:T
              .x:T
                .pr0 (THead (Bind Void) u1 t1) x
                  (or
                       ex3_2 T T λu2:T.λt2:T.eq T x (THead (Bind Void) u2 t2) λu2:T.λ:T.pr0 u1 u2 λ:T.λt2:T.pr0 t1 t2
                       pr0 t1 (lift (S OO x))