DEFINITION pr3_iso_appl_bind()
TYPE =
       b:B
         .not (eq B b Abst)
           v1:T
                .v2:T
                  .t:T
                    .let u1 := THead (Flat Appl) v1 (THead (Bind b) v2 t)
                    in c:C
                           .u2:T
                             .pr3 c u1 u2
                               ((iso u1 u2)P:Prop.P
                                    pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2)
BODY =
        assume bB
        suppose Hnot (eq B b Abst)
        assume v1T
        assume v2T
        assume tT
          we must prove 
                let u1 := THead (Flat Appl) v1 (THead (Bind b) v2 t)
                in c:C
                       .u2:T
                         .pr3 c u1 u2
                           ((iso u1 u2)P:Prop.P
                                pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2)
          or equivalently 
                c:C
                  .u2:T
                    .pr3 c (THead (Flat Appl) v1 (THead (Bind b) v2 t)) u2
                      ((iso (THead (Flat Appl) v1 (THead (Bind b) v2 t)) u2)P:Prop.P
                           pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2)
           assume cC
           assume u2T
           suppose H0pr3 c (THead (Flat Appl) v1 (THead (Bind b) v2 t)) u2
           suppose H1(iso (THead (Flat Appl) v1 (THead (Bind b) v2 t)) u2)P:Prop.P
             (H2
                by (pr3_gen_appl . . . . H0)

                   or3
                     ex3_2
                       T
                       T
                       λu2:T.λt2:T.eq T u2 (THead (Flat Appl) u2 t2)
                       λu2:T.λ:T.pr3 c v1 u2
                       λ:T.λt2:T.pr3 c (THead (Bind b) v2 t) t2
                     ex4_4
                       T
                       T
                       T
                       T
                       λ:T.λ:T.λu2:T.λt2:T.pr3 c (THead (Bind Abbr) u2 t2) u2
                       λ:T.λ:T.λu2:T.λ:T.pr3 c v1 u2
                       λy1:T.λz1:T.λ:T.λ:T.pr3 c (THead (Bind b) v2 t) (THead (Bind Abst) y1 z1)
                       λ:T.λz1:T.λ:T.λt2:T.b:B.u:T.(pr3 (CHead c (Bind b) u) z1 t2)
                     ex6_6
                       B
                       T
                       T
                       T
                       T
                       T
                       λb:B.λ:T.λ:T.λ:T.λ:T.λ:T.not (eq B b Abst)
                       λb:B.λy1:T.λz1:T.λ:T.λ:T.λ:T.pr3 c (THead (Bind b) v2 t) (THead (Bind b) y1 z1)
                       λb:B
                         .λ:T
                           .λ:T
                             .λz2:T.λu2:T.λy2:T.pr3 c (THead (Bind b) y2 (THead (Flat Appl) (lift (S OO u2) z2)) u2
                       λ:B.λ:T.λ:T.λ:T.λu2:T.λ:T.pr3 c v1 u2
                       λ:B.λy1:T.λ:T.λ:T.λ:T.λy2:T.pr3 c y1 y2
                       λb:B.λ:T.λz1:T.λz2:T.λ:T.λy2:T.pr3 (CHead c (Bind b) y2) z1 z2
             end of H2
             we proceed by induction on H2 to prove pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                case or3_intro0 : H3:ex3_2 T T λu3:T.λt2:T.eq T u2 (THead (Flat Appl) u3 t2) λu3:T.λ:T.pr3 c v1 u3 λ:T.λt2:T.pr3 c (THead (Bind b) v2 t) t2 
                   the thesis becomes pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                      we proceed by induction on H3 to prove pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                         case ex3_2_intro : x0:T x1:T H4:eq T u2 (THead (Flat Appl) x0 x1) :pr3 c v1 x0 :pr3 c (THead (Bind b) v2 t) x1 
                            the thesis becomes pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                               (H7
                                  we proceed by induction on H4 to prove 
                                     (iso
                                         THead (Flat Appl) v1 (THead (Bind b) v2 t)
                                         THead (Flat Appl) x0 x1)
                                       P:Prop.P
                                     case refl_equal : 
                                        the thesis becomes the hypothesis H1

                                     (iso
                                         THead (Flat Appl) v1 (THead (Bind b) v2 t)
                                         THead (Flat Appl) x0 x1)
                                       P:Prop.P
                               end of H7
                               by (iso_head . . . . .)
                               we proved 
                                  iso
                                    THead (Flat Appl) v1 (THead (Bind b) v2 t)
                                    THead (Flat Appl) x0 x1
                               by (H7 previous .)
                               we proved 
                                  pr3
                                    c
                                    THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                    THead (Flat Appl) x0 x1
                               by (eq_ind_r . . . previous . H4)
pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                case or3_intro1 : H3:ex4_4 T T T T λ:T.λ:T.λu3:T.λt2:T.pr3 c (THead (Bind Abbr) u3 t2) u2 λ:T.λ:T.λu3:T.λ:T.pr3 c v1 u3 λy1:T.λz1:T.λ:T.λ:T.pr3 c (THead (Bind b) v2 t) (THead (Bind Abst) y1 z1) λ:T.λz1:T.λ:T.λt2:T.b0:B.u:T.(pr3 (CHead c (Bind b0) u) z1 t2) 
                   the thesis becomes pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                      we proceed by induction on H3 to prove pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                         case ex4_4_intro : x0:T x1:T x2:T x3:T H4:pr3 c (THead (Bind Abbr) x2 x3) u2 H5:pr3 c v1 x2 H6:pr3 c (THead (Bind b) v2 t) (THead (Bind Abst) x0 x1) H7:b0:B.u:T.(pr3 (CHead c (Bind b0) u) x1 x3) 
                            the thesis becomes pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                               (H_x
                                  by (pr3_gen_bind . H . . . . H6)

                                     or
                                       ex3_2
                                         T
                                         T
                                         λu2:T.λt2:T.eq T (THead (Bind Abst) x0 x1) (THead (Bind b) u2 t2)
                                         λu2:T.λ:T.pr3 c v2 u2
                                         λ:T.λt2:T.pr3 (CHead c (Bind b) v2) t t2
                                       pr3 (CHead c (Bind b) v2) t (lift (S OO (THead (Bind Abst) x0 x1))
                               end of H_x
                               (H8consider H_x
                               we proceed by induction on H8 to prove 
                                  pr3
                                    c
                                    THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                    THead (Bind Abbr) x2 x3
                                  case or_introl : H9:ex3_2 T T λu3:T.λt2:T.eq T (THead (Bind Abst) x0 x1) (THead (Bind b) u3 t2) λu3:T.λ:T.pr3 c v2 u3 λ:T.λt2:T.pr3 (CHead c (Bind b) v2) t t2 
                                     the thesis becomes 
                                     pr3
                                       c
                                       THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                       THead (Bind Abbr) x2 x3
                                        we proceed by induction on H9 to prove 
                                           pr3
                                             c
                                             THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                             THead (Bind Abbr) x2 x3
                                           case ex3_2_intro : x4:T x5:T H10:eq T (THead (Bind Abst) x0 x1) (THead (Bind b) x4 x5) H11:pr3 c v2 x4 H12:pr3 (CHead c (Bind b) v2) t x5 
                                              the thesis becomes 
                                              pr3
                                                c
                                                THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                THead (Bind Abbr) x2 x3
                                                 (H13
                                                    by (f_equal . . . . . H10)
                                                    we proved 
                                                       eq
                                                         B
                                                         <λ:T.B>
                                                           CASE THead (Bind Abst) x0 x1 OF
                                                             TSort Abst
                                                           | TLRef Abst
                                                           | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat Abst
                                                         <λ:T.B>
                                                           CASE THead (Bind b) x4 x5 OF
                                                             TSort Abst
                                                           | TLRef Abst
                                                           | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat Abst

                                                       eq
                                                         B
                                                         λe:T
                                                             .<λ:T.B>
                                                               CASE e OF
                                                                 TSort Abst
                                                               | TLRef Abst
                                                               | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat Abst
                                                           THead (Bind Abst) x0 x1
                                                         λe:T
                                                             .<λ:T.B>
                                                               CASE e OF
                                                                 TSort Abst
                                                               | TLRef Abst
                                                               | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat Abst
                                                           THead (Bind b) x4 x5
                                                 end of H13
                                                 (h1
                                                    (H14
                                                       by (f_equal . . . . . H10)
                                                       we proved 
                                                          eq
                                                            T
                                                            <λ:T.T> CASE THead (Bind Abst) x0 x1 OF TSort x0 | TLRef x0 | THead  t0 t0
                                                            <λ:T.T> CASE THead (Bind b) x4 x5 OF TSort x0 | TLRef x0 | THead  t0 t0

                                                          eq
                                                            T
                                                            λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead  t0 t0
                                                              THead (Bind Abst) x0 x1
                                                            λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead  t0 t0 (THead (Bind b) x4 x5)
                                                    end of H14
                                                    (h1
                                                       (H15
                                                          by (f_equal . . . . . H10)
                                                          we proved 
                                                             eq
                                                               T
                                                               <λ:T.T> CASE THead (Bind Abst) x0 x1 OF TSort x1 | TLRef x1 | THead   t0t0
                                                               <λ:T.T> CASE THead (Bind b) x4 x5 OF TSort x1 | TLRef x1 | THead   t0t0

                                                             eq
                                                               T
                                                               λe:T.<λ:T.T> CASE e OF TSort x1 | TLRef x1 | THead   t0t0
                                                                 THead (Bind Abst) x0 x1
                                                               λe:T.<λ:T.T> CASE e OF TSort x1 | TLRef x1 | THead   t0t0 (THead (Bind b) x4 x5)
                                                       end of H15
                                                        suppose H16eq T x0 x4
                                                        suppose H17eq B Abst b
                                                          (H18
                                                             consider H15
                                                             we proved 
                                                                eq
                                                                  T
                                                                  <λ:T.T> CASE THead (Bind Abst) x0 x1 OF TSort x1 | TLRef x1 | THead   t0t0
                                                                  <λ:T.T> CASE THead (Bind b) x4 x5 OF TSort x1 | TLRef x1 | THead   t0t0
                                                             that is equivalent to eq T x1 x5
                                                             by (eq_ind_r . . . H12 . previous)
pr3 (CHead c (Bind b) v2) t x1
                                                          end of H18
                                                          (H21
                                                             by (eq_ind_r . . . H . H17)
not (eq B Abst Abst)
                                                          end of H21
                                                          we proceed by induction on H17 to prove 
                                                             pr3
                                                               c
                                                               THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                               THead (Bind Abbr) x2 x3
                                                             case refl_equal : 
                                                                the thesis becomes 
                                                                pr3
                                                                  c
                                                                  THead (Bind Abst) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                                  THead (Bind Abbr) x2 x3
                                                                   (H22
                                                                      by (refl_equal . .)
                                                                      we proved eq B Abst Abst
                                                                      by (H21 previous)
                                                                      we proved False
                                                                      by cases on the previous result we prove 
                                                                         pr3
                                                                           c
                                                                           THead (Bind Abst) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                                           THead (Bind Abbr) x2 x3

                                                                         pr3
                                                                           c
                                                                           THead (Bind Abst) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                                           THead (Bind Abbr) x2 x3
                                                                   end of H22
                                                                   consider H22

                                                                      pr3
                                                                        c
                                                                        THead (Bind Abst) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                                        THead (Bind Abbr) x2 x3
                                                          we proved 
                                                             pr3
                                                               c
                                                               THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                               THead (Bind Abbr) x2 x3

                                                          eq T x0 x4
                                                            (eq B Abst b
                                                                 (pr3
                                                                      c
                                                                      THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                                      THead (Bind Abbr) x2 x3))
                                                    end of h1
                                                    (h2
                                                       consider H14
                                                       we proved 
                                                          eq
                                                            T
                                                            <λ:T.T> CASE THead (Bind Abst) x0 x1 OF TSort x0 | TLRef x0 | THead  t0 t0
                                                            <λ:T.T> CASE THead (Bind b) x4 x5 OF TSort x0 | TLRef x0 | THead  t0 t0
eq T x0 x4
                                                    end of h2
                                                    by (h1 h2)

                                                       eq B Abst b
                                                         (pr3
                                                              c
                                                              THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                              THead (Bind Abbr) x2 x3)
                                                 end of h1
                                                 (h2
                                                    consider H13
                                                    we proved 
                                                       eq
                                                         B
                                                         <λ:T.B>
                                                           CASE THead (Bind Abst) x0 x1 OF
                                                             TSort Abst
                                                           | TLRef Abst
                                                           | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat Abst
                                                         <λ:T.B>
                                                           CASE THead (Bind b) x4 x5 OF
                                                             TSort Abst
                                                           | TLRef Abst
                                                           | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat Abst
eq B Abst b
                                                 end of h2
                                                 by (h1 h2)

                                                    pr3
                                                      c
                                                      THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                      THead (Bind Abbr) x2 x3

                                           pr3
                                             c
                                             THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                             THead (Bind Abbr) x2 x3
                                  case or_intror : H9:pr3 (CHead c (Bind b) v2) t (lift (S OO (THead (Bind Abst) x0 x1)) 
                                     the thesis becomes 
                                     pr3
                                       c
                                       THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                       THead (Bind Abbr) x2 x3
                                        (h1
                                           by (drop_refl .)
                                           we proved drop O O c c
                                           that is equivalent to drop (r (Bind b) OO c c
                                           by (drop_drop . . . . previous .)
                                           we proved drop (S OO (CHead c (Bind b) v2) c
                                           by (pr3_lift . . . . previous . . H5)
                                           we proved pr3 (CHead c (Bind b) v2) (lift (S OO v1) (lift (S OO x2)
                                           by (pr3_flat . . . previous . . H9 .)
                                           we proved 
                                              pr3
                                                CHead c (Bind b) v2
                                                THead (Flat Appl) (lift (S OO v1) t
                                                THead
                                                  Flat Appl
                                                  lift (S OO x2
                                                  lift (S OO (THead (Bind Abst) x0 x1)
                                           by (pr3_head_2 . . . . . previous)

                                              pr3
                                                c
                                                THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                THead
                                                  Bind b
                                                  v2
                                                  THead
                                                    Flat Appl
                                                    lift (S OO x2
                                                    lift (S OO (THead (Bind Abst) x0 x1)
                                        end of h1
                                        (h2
                                           by (lift_flat . . . . .)
                                           we proved 
                                              eq
                                                T
                                                lift (S OO (THead (Flat Appl) x2 (THead (Bind Abst) x0 x1))
                                                THead
                                                  Flat Appl
                                                  lift (S OO x2
                                                  lift (S OO (THead (Bind Abst) x0 x1)
                                           we proceed by induction on the previous result to prove 
                                              pr3
                                                c
                                                THead
                                                  Bind b
                                                  v2
                                                  THead
                                                    Flat Appl
                                                    lift (S OO x2
                                                    lift (S OO (THead (Bind Abst) x0 x1)
                                                THead (Bind Abbr) x2 x3
                                              case refl_equal : 
                                                 the thesis becomes 
                                                 pr3
                                                   c
                                                   THead
                                                     Bind b
                                                     v2
                                                     lift (S OO (THead (Flat Appl) x2 (THead (Bind Abst) x0 x1))
                                                   THead (Bind Abbr) x2 x3
                                                    (h1
                                                       (h1by (pr0_refl .) we proved pr0 x2 x2
                                                       (h2by (pr0_refl .) we proved pr0 x1 x1
                                                       by (pr0_beta . . . h1 . . h2)
                                                       we proved 
                                                          pr0
                                                            THead (Flat Appl) x2 (THead (Bind Abst) x0 x1)
                                                            THead (Bind Abbr) x2 x1
                                                       by (pr0_zeta . H . . previous .)
                                                       we proved 
                                                          pr0
                                                            THead
                                                              Bind b
                                                              v2
                                                              lift (S OO (THead (Flat Appl) x2 (THead (Bind Abst) x0 x1))
                                                            THead (Bind Abbr) x2 x1
                                                       by (pr2_free . . . previous)

                                                          pr2
                                                            c
                                                            THead
                                                              Bind b
                                                              v2
                                                              lift (S OO (THead (Flat Appl) x2 (THead (Bind Abst) x0 x1))
                                                            THead (Bind Abbr) x2 x1
                                                    end of h1
                                                    (h2
                                                       (h1by (pr3_refl . .) we proved pr3 c x2 x2
                                                       (h2
                                                          by (H7 . .)
pr3 (CHead c (Bind Abbr) x2) x1 x3
                                                       end of h2
                                                       by (pr3_head_12 . . . h1 . . . h2)
pr3 c (THead (Bind Abbr) x2 x1) (THead (Bind Abbr) x2 x3)
                                                    end of h2
                                                    by (pr3_sing . . . h1 . h2)

                                                       pr3
                                                         c
                                                         THead
                                                           Bind b
                                                           v2
                                                           lift (S OO (THead (Flat Appl) x2 (THead (Bind Abst) x0 x1))
                                                         THead (Bind Abbr) x2 x3

                                              pr3
                                                c
                                                THead
                                                  Bind b
                                                  v2
                                                  THead
                                                    Flat Appl
                                                    lift (S OO x2
                                                    lift (S OO (THead (Bind Abst) x0 x1)
                                                THead (Bind Abbr) x2 x3
                                        end of h2
                                        by (pr3_t . . . h1 . h2)

                                           pr3
                                             c
                                             THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                             THead (Bind Abbr) x2 x3
                               we proved 
                                  pr3
                                    c
                                    THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                    THead (Bind Abbr) x2 x3
                               by (pr3_t . . . previous . H4)
pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                case or3_intro2 : H3:ex6_6 B T T T T T λb0:B.λ:T.λ:T.λ:T.λ:T.λ:T.not (eq B b0 Abstλb0:B.λy1:T.λz1:T.λ:T.λ:T.λ:T.pr3 c (THead (Bind b) v2 t) (THead (Bind b0) y1 z1) λb0:B.λ:T.λ:T.λz2:T.λu3:T.λy2:T.pr3 c (THead (Bind b0) y2 (THead (Flat Appl) (lift (S OO u3) z2)) u2 λ:B.λ:T.λ:T.λ:T.λu3:T.λ:T.pr3 c v1 u3 λ:B.λy1:T.λ:T.λ:T.λ:T.λy2:T.pr3 c y1 y2 λb0:B.λ:T.λz1:T.λz2:T.λ:T.λy2:T.pr3 (CHead c (Bind b0) y2) z1 z2 
                   the thesis becomes pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                      we proceed by induction on H3 to prove pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                         case ex6_6_intro : x0:B x1:T x2:T x3:T x4:T x5:T H4:not (eq B x0 Abst) H5:pr3 c (THead (Bind b) v2 t) (THead (Bind x0) x1 x2) H6:pr3 c (THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)) u2 H7:pr3 c v1 x4 H8:pr3 c x1 x5 H9:pr3 (CHead c (Bind x0) x5) x2 x3 
                            the thesis becomes pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
                               (H_x
                                  by (pr3_gen_bind . H . . . . H5)

                                     or
                                       ex3_2
                                         T
                                         T
                                         λu2:T.λt2:T.eq T (THead (Bind x0) x1 x2) (THead (Bind b) u2 t2)
                                         λu2:T.λ:T.pr3 c v2 u2
                                         λ:T.λt2:T.pr3 (CHead c (Bind b) v2) t t2
                                       pr3 (CHead c (Bind b) v2) t (lift (S OO (THead (Bind x0) x1 x2))
                               end of H_x
                               (H10consider H_x
                               we proceed by induction on H10 to prove 
                                  pr3
                                    c
                                    THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                    THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                                  case or_introl : H11:ex3_2 T T λu3:T.λt2:T.eq T (THead (Bind x0) x1 x2) (THead (Bind b) u3 t2) λu3:T.λ:T.pr3 c v2 u3 λ:T.λt2:T.pr3 (CHead c (Bind b) v2) t t2 
                                     the thesis becomes 
                                     pr3
                                       c
                                       THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                       THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                                        we proceed by induction on H11 to prove 
                                           pr3
                                             c
                                             THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                             THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                                           case ex3_2_intro : x6:T x7:T H12:eq T (THead (Bind x0) x1 x2) (THead (Bind b) x6 x7) H13:pr3 c v2 x6 H14:pr3 (CHead c (Bind b) v2) t x7 
                                              the thesis becomes 
                                              pr3
                                                c
                                                THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                                                 (H15
                                                    by (f_equal . . . . . H12)
                                                    we proved 
                                                       eq
                                                         B
                                                         <λ:T.B>
                                                           CASE THead (Bind x0) x1 x2 OF
                                                             TSort x0
                                                           | TLRef x0
                                                           | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat x0
                                                         <λ:T.B>
                                                           CASE THead (Bind b) x6 x7 OF
                                                             TSort x0
                                                           | TLRef x0
                                                           | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat x0

                                                       eq
                                                         B
                                                         λe:T
                                                             .<λ:T.B>
                                                               CASE e OF
                                                                 TSort x0
                                                               | TLRef x0
                                                               | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat x0
                                                           THead (Bind x0) x1 x2
                                                         λe:T
                                                             .<λ:T.B>
                                                               CASE e OF
                                                                 TSort x0
                                                               | TLRef x0
                                                               | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat x0
                                                           THead (Bind b) x6 x7
                                                 end of H15
                                                 (h1
                                                    (H16
                                                       by (f_equal . . . . . H12)
                                                       we proved 
                                                          eq
                                                            T
                                                            <λ:T.T> CASE THead (Bind x0) x1 x2 OF TSort x1 | TLRef x1 | THead  t0 t0
                                                            <λ:T.T> CASE THead (Bind b) x6 x7 OF TSort x1 | TLRef x1 | THead  t0 t0

                                                          eq
                                                            T
                                                            λe:T.<λ:T.T> CASE e OF TSort x1 | TLRef x1 | THead  t0 t0 (THead (Bind x0) x1 x2)
                                                            λe:T.<λ:T.T> CASE e OF TSort x1 | TLRef x1 | THead  t0 t0 (THead (Bind b) x6 x7)
                                                    end of H16
                                                    (h1
                                                       (H17
                                                          by (f_equal . . . . . H12)
                                                          we proved 
                                                             eq
                                                               T
                                                               <λ:T.T> CASE THead (Bind x0) x1 x2 OF TSort x2 | TLRef x2 | THead   t0t0
                                                               <λ:T.T> CASE THead (Bind b) x6 x7 OF TSort x2 | TLRef x2 | THead   t0t0

                                                             eq
                                                               T
                                                               λe:T.<λ:T.T> CASE e OF TSort x2 | TLRef x2 | THead   t0t0 (THead (Bind x0) x1 x2)
                                                               λe:T.<λ:T.T> CASE e OF TSort x2 | TLRef x2 | THead   t0t0 (THead (Bind b) x6 x7)
                                                       end of H17
                                                        suppose H18eq T x1 x6
                                                        suppose H19eq B x0 b
                                                          (H20
                                                             consider H17
                                                             we proved 
                                                                eq
                                                                  T
                                                                  <λ:T.T> CASE THead (Bind x0) x1 x2 OF TSort x2 | TLRef x2 | THead   t0t0
                                                                  <λ:T.T> CASE THead (Bind b) x6 x7 OF TSort x2 | TLRef x2 | THead   t0t0
                                                             that is equivalent to eq T x2 x7
                                                             by (eq_ind_r . . . H14 . previous)
pr3 (CHead c (Bind b) v2) t x2
                                                          end of H20
                                                          (H21
                                                             by (eq_ind_r . . . H13 . H18)
pr3 c v2 x1
                                                          end of H21
                                                          (H22
                                                             we proceed by induction on H19 to prove pr3 (CHead c (Bind b) x5) x2 x3
                                                                case refl_equal : 
                                                                   the thesis becomes the hypothesis H9
pr3 (CHead c (Bind b) x5) x2 x3
                                                          end of H22
                                                          (h1by (pr3_t . . . H21 . H8) we proved pr3 c v2 x5
                                                          (h2
                                                             (h1
                                                                by (drop_refl .)
                                                                we proved drop O O c c
                                                                that is equivalent to drop (r (Bind b) OO c c
                                                                by (drop_drop . . . . previous .)
                                                                we proved drop (S OO (CHead c (Bind b) v2) c
                                                                by (pr3_lift . . . . previous . . H7)
pr3 (CHead c (Bind b) v2) (lift (S OO v1) (lift (S OO x4)
                                                             end of h1
                                                             (h2
                                                                by (pr3_pr3_pr3_t . . . H8 . . . H22)
                                                                we proved pr3 (CHead c (Bind b) x1) x2 x3
                                                                by (pr3_pr3_pr3_t . . . H21 . . . previous)
                                                                we proved pr3 (CHead c (Bind b) v2) x2 x3
                                                                by (pr3_t . . . H20 . previous)
pr3 (CHead c (Bind b) v2) t x3
                                                             end of h2
                                                             by (pr3_flat . . . h1 . . h2 .)

                                                                pr3
                                                                  CHead c (Bind b) v2
                                                                  THead (Flat Appl) (lift (S OO v1) t
                                                                  THead (Flat Appl) (lift (S OO x4) x3
                                                          end of h2
                                                          by (pr3_head_21 . . . h1 . . . h2)
                                                          we proved 
                                                             pr3
                                                               c
                                                               THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                               THead (Bind b) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                                                          by (eq_ind_r . . . previous . H19)
                                                          we proved 
                                                             pr3
                                                               c
                                                               THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                               THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)

                                                          eq T x1 x6
                                                            (eq B x0 b
                                                                 (pr3
                                                                      c
                                                                      THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                                      THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)))
                                                    end of h1
                                                    (h2
                                                       consider H16
                                                       we proved 
                                                          eq
                                                            T
                                                            <λ:T.T> CASE THead (Bind x0) x1 x2 OF TSort x1 | TLRef x1 | THead  t0 t0
                                                            <λ:T.T> CASE THead (Bind b) x6 x7 OF TSort x1 | TLRef x1 | THead  t0 t0
eq T x1 x6
                                                    end of h2
                                                    by (h1 h2)

                                                       eq B x0 b
                                                         (pr3
                                                              c
                                                              THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                              THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3))
                                                 end of h1
                                                 (h2
                                                    consider H15
                                                    we proved 
                                                       eq
                                                         B
                                                         <λ:T.B>
                                                           CASE THead (Bind x0) x1 x2 OF
                                                             TSort x0
                                                           | TLRef x0
                                                           | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat x0
                                                         <λ:T.B>
                                                           CASE THead (Bind b) x6 x7 OF
                                                             TSort x0
                                                           | TLRef x0
                                                           | THead k  <λ:K.B> CASE k OF Bind b0b0 | Flat x0
eq B x0 b
                                                 end of h2
                                                 by (h1 h2)

                                                    pr3
                                                      c
                                                      THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                      THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)

                                           pr3
                                             c
                                             THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                             THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                                  case or_intror : H11:pr3 (CHead c (Bind b) v2) t (lift (S OO (THead (Bind x0) x1 x2)) 
                                     the thesis becomes 
                                     pr3
                                       c
                                       THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                       THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                                        (h1
                                           by (drop_refl .)
                                           we proved drop O O c c
                                           that is equivalent to drop (r (Bind b) OO c c
                                           by (drop_drop . . . . previous .)
                                           we proved drop (S OO (CHead c (Bind b) v2) c
                                           by (pr3_lift . . . . previous . . H7)
                                           we proved pr3 (CHead c (Bind b) v2) (lift (S OO v1) (lift (S OO x4)
                                           by (pr3_flat . . . previous . . H11 .)
                                           we proved 
                                              pr3
                                                CHead c (Bind b) v2
                                                THead (Flat Appl) (lift (S OO v1) t
                                                THead
                                                  Flat Appl
                                                  lift (S OO x4
                                                  lift (S OO (THead (Bind x0) x1 x2)
                                           by (pr3_head_2 . . . . . previous)

                                              pr3
                                                c
                                                THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                                THead
                                                  Bind b
                                                  v2
                                                  THead
                                                    Flat Appl
                                                    lift (S OO x4
                                                    lift (S OO (THead (Bind x0) x1 x2)
                                        end of h1
                                        (h2
                                           by (lift_flat . . . . .)
                                           we proved 
                                              eq
                                                T
                                                lift (S OO (THead (Flat Appl) x4 (THead (Bind x0) x1 x2))
                                                THead
                                                  Flat Appl
                                                  lift (S OO x4
                                                  lift (S OO (THead (Bind x0) x1 x2)
                                           we proceed by induction on the previous result to prove 
                                              pr3
                                                c
                                                THead
                                                  Bind b
                                                  v2
                                                  THead
                                                    Flat Appl
                                                    lift (S OO x4
                                                    lift (S OO (THead (Bind x0) x1 x2)
                                                THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                                              case refl_equal : 
                                                 the thesis becomes 
                                                 pr3
                                                   c
                                                   THead
                                                     Bind b
                                                     v2
                                                     lift (S OO (THead (Flat Appl) x4 (THead (Bind x0) x1 x2))
                                                   THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                                                    (h1
                                                       (h1by (pr0_refl .) we proved pr0 x4 x4
                                                       (h2by (pr0_refl .) we proved pr0 x1 x1
                                                       (h3by (pr0_refl .) we proved pr0 x2 x2
                                                       by (pr0_upsilon . H4 . . h1 . . h2 . . h3)
                                                       we proved 
                                                          pr0
                                                            THead (Flat Appl) x4 (THead (Bind x0) x1 x2)
                                                            THead (Bind x0) x1 (THead (Flat Appl) (lift (S OO x4) x2)
                                                       by (pr0_zeta . H . . previous .)
                                                       we proved 
                                                          pr0
                                                            THead
                                                              Bind b
                                                              v2
                                                              lift (S OO (THead (Flat Appl) x4 (THead (Bind x0) x1 x2))
                                                            THead (Bind x0) x1 (THead (Flat Appl) (lift (S OO x4) x2)
                                                       by (pr2_free . . . previous)

                                                          pr2
                                                            c
                                                            THead
                                                              Bind b
                                                              v2
                                                              lift (S OO (THead (Flat Appl) x4 (THead (Bind x0) x1 x2))
                                                            THead (Bind x0) x1 (THead (Flat Appl) (lift (S OO x4) x2)
                                                    end of h1
                                                    (h2
                                                       by (pr3_thin_dx . . . H9 . .)
                                                       we proved 
                                                          pr3
                                                            CHead c (Bind x0) x5
                                                            THead (Flat Appl) (lift (S OO x4) x2
                                                            THead (Flat Appl) (lift (S OO x4) x3
                                                       by (pr3_head_12 . . . H8 . . . previous)

                                                          pr3
                                                            c
                                                            THead (Bind x0) x1 (THead (Flat Appl) (lift (S OO x4) x2)
                                                            THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                                                    end of h2
                                                    by (pr3_sing . . . h1 . h2)

                                                       pr3
                                                         c
                                                         THead
                                                           Bind b
                                                           v2
                                                           lift (S OO (THead (Flat Appl) x4 (THead (Bind x0) x1 x2))
                                                         THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)

                                              pr3
                                                c
                                                THead
                                                  Bind b
                                                  v2
                                                  THead
                                                    Flat Appl
                                                    lift (S OO x4
                                                    lift (S OO (THead (Bind x0) x1 x2)
                                                THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                                        end of h2
                                        by (pr3_t . . . h1 . h2)

                                           pr3
                                             c
                                             THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                             THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                               we proved 
                                  pr3
                                    c
                                    THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)
                                    THead (Bind x0) x5 (THead (Flat Appl) (lift (S OO x4) x3)
                               by (pr3_t . . . previous . H6)
pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
             we proved pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2
          we proved 
             c:C
               .u2:T
                 .pr3 c (THead (Flat Appl) v1 (THead (Bind b) v2 t)) u2
                   ((iso (THead (Flat Appl) v1 (THead (Bind b) v2 t)) u2)P:Prop.P
                        pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2)
          that is equivalent to 
             let u1 := THead (Flat Appl) v1 (THead (Bind b) v2 t)
             in c:C
                    .u2:T
                      .pr3 c u1 u2
                        ((iso u1 u2)P:Prop.P
                             pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2)
       we proved 
          b:B
            .not (eq B b Abst)
              v1:T
                   .v2:T
                     .t:T
                       .let u1 := THead (Flat Appl) v1 (THead (Bind b) v2 t)
                       in c:C
                              .u2:T
                                .pr3 c u1 u2
                                  ((iso u1 u2)P:Prop.P
                                       pr3 c (THead (Bind b) v2 (THead (Flat Appl) (lift (S OO v1) t)) u2)