DEFINITION pc3_abst_dec()
TYPE =
       g:G
         .c:C
           .u1:T
             .t1:T
               .ty3 g c u1 t1
                 u2:T
                      .t2:T
                        .ty3 g c u2 t2
                          (or
                               ex4_2
                                 T
                                 T
                                 λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                 λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                 λ:T.λv2:T.pr3 c u2 v2
                                 λ:T.λv2:T.nf2 c v2
                               u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False)
BODY =
        assume gG
        assume cC
        assume u1T
        assume t1T
        suppose Hty3 g c u1 t1
        assume u2T
        assume t2T
        suppose H0ty3 g c u2 t2
          (H1by (ty3_sn3 . . . . H) we proved sn3 c u1
          (H2by (ty3_sn3 . . . . H0) we proved sn3 c u2
          (H_x
             by (nf2_sn3 . . H1)
ex2 T λu:T.pr3 c u1 u λu:T.nf2 c u
          end of H_x
          (H3consider H_x
          we proceed by induction on H3 to prove 
             or
               ex4_2
                 T
                 T
                 λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                 λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                 λ:T.λv2:T.pr3 c u2 v2
                 λ:T.λv2:T.nf2 c v2
               u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
             case ex_intro2 : x:T H4:pr3 c u1 x H5:nf2 c x 
                the thesis becomes 
                or
                  ex4_2
                    T
                    T
                    λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                    λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                    λ:T.λv2:T.pr3 c u2 v2
                    λ:T.λv2:T.nf2 c v2
                  u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
                   (H_x0
                      by (nf2_sn3 . . H2)
ex2 T λu:T.pr3 c u2 u λu:T.nf2 c u
                   end of H_x0
                   (H6consider H_x0
                   we proceed by induction on H6 to prove 
                      or
                        ex4_2
                          T
                          T
                          λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                          λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                          λ:T.λv2:T.pr3 c u2 v2
                          λ:T.λv2:T.nf2 c v2
                        u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
                      case ex_intro2 : x0:T H7:pr3 c u2 x0 H8:nf2 c x0 
                         the thesis becomes 
                         or
                           ex4_2
                             T
                             T
                             λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                             λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                             λ:T.λv2:T.pr3 c u2 v2
                             λ:T.λv2:T.nf2 c v2
                           u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
                            (H_x1
                               by (abst_dec . .)

                                  or
                                    ex T λt:T.eq T x (THead (Bind Abst) x0 t)
                                    t:T.(eq T x (THead (Bind Abst) x0 t))P:Prop.P
                            end of H_x1
                            (H9consider H_x1
                            we proceed by induction on H9 to prove 
                               or
                                 ex4_2
                                   T
                                   T
                                   λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                   λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                   λ:T.λv2:T.pr3 c u2 v2
                                   λ:T.λv2:T.nf2 c v2
                                 u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
                               case or_introl : H10:ex T λt:T.eq T x (THead (Bind Abst) x0 t) 
                                  the thesis becomes 
                                  or
                                    ex4_2
                                      T
                                      T
                                      λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                      λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                      λ:T.λv2:T.pr3 c u2 v2
                                      λ:T.λv2:T.nf2 c v2
                                    u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
                                     we proceed by induction on H10 to prove 
                                        or
                                          ex4_2
                                            T
                                            T
                                            λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                            λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                            λ:T.λv2:T.pr3 c u2 v2
                                            λ:T.λv2:T.nf2 c v2
                                          u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
                                        case ex_intro : x1:T H11:eq T x (THead (Bind Abst) x0 x1) 
                                           the thesis becomes 
                                           or
                                             ex4_2
                                               T
                                               T
                                               λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                               λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                               λ:T.λv2:T.pr3 c u2 v2
                                               λ:T.λv2:T.nf2 c v2
                                             u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
                                              (H13
                                                 we proceed by induction on H11 to prove pr3 c u1 (THead (Bind Abst) x0 x1)
                                                    case refl_equal : 
                                                       the thesis becomes the hypothesis H4
pr3 c u1 (THead (Bind Abst) x0 x1)
                                              end of H13
                                              (H_y
                                                 by (ty3_sred_pr3 . . . H13 . . H)
ty3 g c (THead (Bind Abst) x0 x1) t1
                                              end of H_y
                                              by (pr3_refl . .)
                                              we proved pr3 (CHead c (Bind Abst) x0) x1 x1
                                              by (pr3_head_12 . . . H7 . . . previous)
                                              we proved pr3 c (THead (Bind Abst) u2 x1) (THead (Bind Abst) x0 x1)
                                              by (pc3_pr3_t . . . H13 . previous)
                                              we proved pc3 c u1 (THead (Bind Abst) u2 x1)
                                              by (ex4_2_intro . . . . . . . . previous H_y H7 H8)
                                              we proved 
                                                 ex4_2
                                                   T
                                                   T
                                                   λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                                   λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                                   λ:T.λv2:T.pr3 c u2 v2
                                                   λ:T.λv2:T.nf2 c v2
                                              by (or_introl . . previous)

                                                 or
                                                   ex4_2
                                                     T
                                                     T
                                                     λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                                     λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                                     λ:T.λv2:T.pr3 c u2 v2
                                                     λ:T.λv2:T.nf2 c v2
                                                   u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False

                                        or
                                          ex4_2
                                            T
                                            T
                                            λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                            λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                            λ:T.λv2:T.pr3 c u2 v2
                                            λ:T.λv2:T.nf2 c v2
                                          u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
                               case or_intror : H10:t:T.(eq T x (THead (Bind Abst) x0 t))P:Prop.P 
                                  the thesis becomes 
                                  or
                                    ex4_2
                                      T
                                      T
                                      λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                      λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                      λ:T.λv2:T.pr3 c u2 v2
                                      λ:T.λv2:T.nf2 c v2
                                    u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
                                      assume uT
                                      suppose H11pc3 c u1 (THead (Bind Abst) u2 u)
                                        (H12consider H11
                                        consider H12
                                        we proved pc3 c u1 (THead (Bind Abst) u2 u)
                                        that is equivalent to ex2 T λt:T.pr3 c u1 t λt:T.pr3 c (THead (Bind Abst) u2 u) t
                                        we proceed by induction on the previous result to prove False
                                           case ex_intro2 : x1:T H13:pr3 c u1 x1 H14:pr3 c (THead (Bind Abst) u2 u) x1 
                                              the thesis becomes False
                                                 by (pr3_confluence . . . H13 . H4)
                                                 we proved ex2 T λt:T.pr3 c x1 t λt:T.pr3 c x t
                                                 we proceed by induction on the previous result to prove False
                                                    case ex_intro2 : x2:T H15:pr3 c x1 x2 H16:pr3 c x x2 
                                                       the thesis becomes False
                                                          (H_y
                                                             by (nf2_pr3_unfold . . . H16 H5)
eq T x x2
                                                          end of H_y
                                                          (H17
                                                             by (eq_ind_r . . . H15 . H_y)
pr3 c x1 x
                                                          end of H17
                                                          (H18
                                                             by (pr3_gen_abst . . . . H14)

                                                                ex3_2
                                                                  T
                                                                  T
                                                                  λu2:T.λt2:T.eq T x1 (THead (Bind Abst) u2 t2)
                                                                  λu2:T.λ:T.pr3 c u2 u2
                                                                  λ:T.λt2:T.b:B.u:T.(pr3 (CHead c (Bind b) u) u t2)
                                                          end of H18
                                                          we proceed by induction on H18 to prove False
                                                             case ex3_2_intro : x3:T x4:T H19:eq T x1 (THead (Bind Abst) x3 x4) H20:pr3 c u2 x3 :b:B.u0:T.(pr3 (CHead c (Bind b) u0) u x4) 
                                                                the thesis becomes False
                                                                   (H22
                                                                      we proceed by induction on H19 to prove pr3 c (THead (Bind Abst) x3 x4) x
                                                                         case refl_equal : 
                                                                            the thesis becomes the hypothesis H17
pr3 c (THead (Bind Abst) x3 x4) x
                                                                   end of H22
                                                                   (H23
                                                                      by (pr3_gen_abst . . . . H22)

                                                                         ex3_2
                                                                           T
                                                                           T
                                                                           λu2:T.λt2:T.eq T x (THead (Bind Abst) u2 t2)
                                                                           λu2:T.λ:T.pr3 c x3 u2
                                                                           λ:T.λt2:T.b:B.u:T.(pr3 (CHead c (Bind b) u) x4 t2)
                                                                   end of H23
                                                                   we proceed by induction on H23 to prove False
                                                                      case ex3_2_intro : x5:T x6:T H24:eq T x (THead (Bind Abst) x5 x6) H25:pr3 c x3 x5 :b:B.u0:T.(pr3 (CHead c (Bind b) u0) x4 x6) 
                                                                         the thesis becomes False
                                                                            (H27
                                                                               we proceed by induction on H24 to prove 
                                                                                  t0:T
                                                                                    .(eq T (THead (Bind Abst) x5 x6) (THead (Bind Abst) x0 t0))P:Prop.P
                                                                                  case refl_equal : 
                                                                                     the thesis becomes the hypothesis H10

                                                                                  t0:T
                                                                                    .(eq T (THead (Bind Abst) x5 x6) (THead (Bind Abst) x0 t0))P:Prop.P
                                                                            end of H27
                                                                            (H28
                                                                               we proceed by induction on H24 to prove nf2 c (THead (Bind Abst) x5 x6)
                                                                                  case refl_equal : 
                                                                                     the thesis becomes the hypothesis H5
nf2 c (THead (Bind Abst) x5 x6)
                                                                            end of H28
                                                                            (H29
                                                                               by (nf2_gen_abst . . . H28)
land (nf2 c x5) (nf2 (CHead c (Bind Abst) x5) x6)
                                                                            end of H29
                                                                            we proceed by induction on H29 to prove False
                                                                               case conj : H30:nf2 c x5 :nf2 (CHead c (Bind Abst) x5) x6 
                                                                                  the thesis becomes False
                                                                                     (H32
                                                                                        by (nf2_pr3_confluence . . H8 . H30 . H7)
(pr3 c u2 x5)(eq T x0 x5)
                                                                                     end of H32
                                                                                     (h1
                                                                                        by (refl_equal . .)
eq K (Bind Abst) (Bind Abst)
                                                                                     end of h1
                                                                                     (h2
                                                                                        by (pr3_t . . . H20 . H25)
                                                                                        we proved pr3 c u2 x5
                                                                                        by (H32 previous)
eq T x0 x5
                                                                                     end of h2
                                                                                     (h3
                                                                                        by (refl_equal . .)
eq T x6 x6
                                                                                     end of h3
                                                                                     by (f_equal3 . . . . . . . . . . . h1 h2 h3)
                                                                                     we proved eq T (THead (Bind Abst) x0 x6) (THead (Bind Abst) x5 x6)
                                                                                     by (sym_eq . . . previous)
                                                                                     we proved eq T (THead (Bind Abst) x5 x6) (THead (Bind Abst) x0 x6)
                                                                                     by (H27 . previous .)
False
False
False
False
False
                                        we proved False
                                     we proved u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
                                     by (or_intror . . previous)

                                        or
                                          ex4_2
                                            T
                                            T
                                            λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                            λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                            λ:T.λv2:T.pr3 c u2 v2
                                            λ:T.λv2:T.nf2 c v2
                                          u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False

                               or
                                 ex4_2
                                   T
                                   T
                                   λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                   λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                   λ:T.λv2:T.pr3 c u2 v2
                                   λ:T.λv2:T.nf2 c v2
                                 u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False

                      or
                        ex4_2
                          T
                          T
                          λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                          λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                          λ:T.λv2:T.pr3 c u2 v2
                          λ:T.λv2:T.nf2 c v2
                        u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
          we proved 
             or
               ex4_2
                 T
                 T
                 λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                 λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                 λ:T.λv2:T.pr3 c u2 v2
                 λ:T.λv2:T.nf2 c v2
               u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False
       we proved 
          g:G
            .c:C
              .u1:T
                .t1:T
                  .ty3 g c u1 t1
                    u2:T
                         .t2:T
                           .ty3 g c u2 t2
                             (or
                                  ex4_2
                                    T
                                    T
                                    λu:T.λ:T.pc3 c u1 (THead (Bind Abst) u2 u)
                                    λu:T.λv2:T.ty3 g c (THead (Bind Abst) v2 u) t1
                                    λ:T.λv2:T.pr3 c u2 v2
                                    λ:T.λv2:T.nf2 c v2
                                  u:T.(pc3 c u1 (THead (Bind Abst) u2 u))False)