DEFINITION sn3_beta()
TYPE =
       c:C
         .v:T
           .t:T
             .sn3 c (THead (Bind Abbr) v t)
               w:T
                    .(sn3 c w)(sn3 c (THead (Flat Appl) v (THead (Bind Abst) w t)))
BODY =
        assume cC
        assume vT
        assume tT
        suppose Hsn3 c (THead (Bind Abbr) v t)
           assume yT
           suppose H0sn3 c y
             we proceed by induction on H0 to prove 
                x:T
                  .x0:T
                    .eq T y (THead (Bind Abbr) x x0)
                      w:T
                           .(sn3 c w)(sn3 c (THead (Flat Appl) x (THead (Bind Abst) w x0)))
                case sn3_sing : t1:T H1:t2:T.((eq T t1 t2)P:Prop.P)(pr3 c t1 t2)(sn3 c t2) 
                   the thesis becomes 
                   x:T
                     .x0:T
                       .H3:eq T t1 (THead (Bind Abbr) x x0)
                         .w:T.H4:(sn3 c w).(sn3 c (THead (Flat Appl) x (THead (Bind Abst) w x0)))
                   (H2) by induction hypothesis we know 
                      t2:T
                        .(eq T t1 t2)P:Prop.P
                          (pr3 c t1 t2
                               x:T
                                    .x0:T
                                      .eq T t2 (THead (Bind Abbr) x x0)
                                        w:T
                                             .(sn3 c w)(sn3 c (THead (Flat Appl) x (THead (Bind Abst) w x0))))
                       assume xT
                       assume x0T
                       suppose H3eq T t1 (THead (Bind Abbr) x x0)
                       assume wT
                       suppose H4sn3 c w
                         (H5
                            we proceed by induction on H3 to prove 
                               t2:T
                                 .(eq T (THead (Bind Abbr) x x0) t2)P:Prop.P
                                   (pr3 c (THead (Bind Abbr) x x0) t2
                                        x1:T
                                             .x2:T
                                               .eq T t2 (THead (Bind Abbr) x1 x2)
                                                 w0:T.(sn3 c w0)(sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) w0 x2))))
                               case refl_equal : 
                                  the thesis becomes the hypothesis H2

                               t2:T
                                 .(eq T (THead (Bind Abbr) x x0) t2)P:Prop.P
                                   (pr3 c (THead (Bind Abbr) x x0) t2
                                        x1:T
                                             .x2:T
                                               .eq T t2 (THead (Bind Abbr) x1 x2)
                                                 w0:T.(sn3 c w0)(sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) w0 x2))))
                         end of H5
                         (H6
                            we proceed by induction on H3 to prove 
                               t2:T
                                 .(eq T (THead (Bind Abbr) x x0) t2)P:Prop.P
                                   (pr3 c (THead (Bind Abbr) x x0) t2)(sn3 c t2)
                               case refl_equal : 
                                  the thesis becomes the hypothesis H1

                               t2:T
                                 .(eq T (THead (Bind Abbr) x x0) t2)P:Prop.P
                                   (pr3 c (THead (Bind Abbr) x x0) t2)(sn3 c t2)
                         end of H6
                         we proceed by induction on H4 to prove sn3 c (THead (Flat Appl) x (THead (Bind Abst) w x0))
                            case sn3_sing : t2:T H7:t3:T.((eq T t2 t3)P:Prop.P)(pr3 c t2 t3)(sn3 c t3) 
                               the thesis becomes sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x0))
                               (H8) by induction hypothesis we know 
                                  t3:T
                                    .(eq T t2 t3)P:Prop.P
                                      (pr3 c t2 t3)(sn3 c (THead (Flat Appl) x (THead (Bind Abst) t3 x0)))
                                   assume t3T
                                   suppose H9
                                      eq T (THead (Flat Appl) x (THead (Bind Abst) t2 x0)) t3
                                        P:Prop.P
                                   suppose H10pr2 c (THead (Flat Appl) x (THead (Bind Abst) t2 x0)) t3
                                     (H11
                                        by (pr2_gen_appl . . . . H10)

                                           or3
                                             ex3_2
                                               T
                                               T
                                               λu2:T.λt2:T.eq T t3 (THead (Flat Appl) u2 t2)
                                               λu2:T.λ:T.pr2 c x u2
                                               λ:T.λt2:T.pr2 c (THead (Bind Abst) t2 x0) t2
                                             ex4_4
                                               T
                                               T
                                               T
                                               T
                                               λy1:T.λz1:T.λ:T.λ:T.eq T (THead (Bind Abst) t2 x0) (THead (Bind Abst) y1 z1)
                                               λ:T.λ:T.λu2:T.λt2:T.eq T t3 (THead (Bind Abbr) u2 t2)
                                               λ:T.λ:T.λu2:T.λ:T.pr2 c x u2
                                               λ:T.λz1:T.λ:T.λt2:T.b:B.u:T.(pr2 (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.eq T (THead (Bind Abst) t2 x0) (THead (Bind b) y1 z1)
                                               λb:B
                                                 .λ:T
                                                   .λ:T
                                                     .λz2:T
                                                       .λu2:T
                                                         .λy2:T.eq T t3 (THead (Bind b) y2 (THead (Flat Appl) (lift (S OO u2) z2))
                                               λ:B.λ:T.λ:T.λ:T.λu2:T.λ:T.pr2 c x u2
                                               λ:B.λy1:T.λ:T.λ:T.λ:T.λy2:T.pr2 c y1 y2
                                               λb:B.λ:T.λz1:T.λz2:T.λ:T.λy2:T.pr2 (CHead c (Bind b) y2) z1 z2
                                     end of H11
                                     we proceed by induction on H11 to prove sn3 c t3
                                        case or3_intro0 : H12:ex3_2 T T λu2:T.λt4:T.eq T t3 (THead (Flat Appl) u2 t4) λu2:T.λ:T.pr2 c x u2 λ:T.λt4:T.pr2 c (THead (Bind Abst) t2 x0) t4 
                                           the thesis becomes sn3 c t3
                                              we proceed by induction on H12 to prove sn3 c t3
                                                 case ex3_2_intro : x1:T x2:T H13:eq T t3 (THead (Flat Appl) x1 x2) H14:pr2 c x x1 H15:pr2 c (THead (Bind Abst) t2 x0) x2 
                                                    the thesis becomes sn3 c t3
                                                       (H16
                                                          we proceed by induction on H13 to prove 
                                                             (eq
                                                                 T
                                                                 THead (Flat Appl) x (THead (Bind Abst) t2 x0)
                                                                 THead (Flat Appl) x1 x2)
                                                               P:Prop.P
                                                             case refl_equal : 
                                                                the thesis becomes the hypothesis H9

                                                             (eq
                                                                 T
                                                                 THead (Flat Appl) x (THead (Bind Abst) t2 x0)
                                                                 THead (Flat Appl) x1 x2)
                                                               P:Prop.P
                                                       end of H16
                                                       (H17
                                                          by (pr2_gen_abst . . . . H15)

                                                             ex3_2
                                                               T
                                                               T
                                                               λu2:T.λt2:T.eq T x2 (THead (Bind Abst) u2 t2)
                                                               λu2:T.λ:T.pr2 c t2 u2
                                                               λ:T.λt2:T.b:B.u:T.(pr2 (CHead c (Bind b) u) x0 t2)
                                                       end of H17
                                                       we proceed by induction on H17 to prove sn3 c (THead (Flat Appl) x1 x2)
                                                          case ex3_2_intro : x3:T x4:T H18:eq T x2 (THead (Bind Abst) x3 x4) H19:pr2 c t2 x3 H20:b:B.u:T.(pr2 (CHead c (Bind b) u) x0 x4) 
                                                             the thesis becomes sn3 c (THead (Flat Appl) x1 x2)
                                                                (H21
                                                                   we proceed by induction on H18 to prove 
                                                                      (eq
                                                                          T
                                                                          THead (Flat Appl) x (THead (Bind Abst) t2 x0)
                                                                          THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                        P:Prop.P
                                                                      case refl_equal : 
                                                                         the thesis becomes the hypothesis H16

                                                                      (eq
                                                                          T
                                                                          THead (Flat Appl) x (THead (Bind Abst) t2 x0)
                                                                          THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                        P:Prop.P
                                                                end of H21
                                                                (H_x
                                                                   by (term_dec . .)
or (eq T t2 x3) (eq T t2 x3)P:Prop.P
                                                                end of H_x
                                                                (H22consider H_x
                                                                we proceed by induction on H22 to prove sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                   case or_introl : H23:eq T t2 x3 
                                                                      the thesis becomes sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                         (H24
                                                                            by (eq_ind_r . . . H21 . H23)

                                                                               (eq
                                                                                   T
                                                                                   THead (Flat Appl) x (THead (Bind Abst) t2 x0)
                                                                                   THead (Flat Appl) x1 (THead (Bind Abst) t2 x4))
                                                                                 P:Prop.P
                                                                         end of H24
                                                                         we proceed by induction on H23 to prove sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                            case refl_equal : 
                                                                               the thesis becomes sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) t2 x4))
                                                                                  (H_x0
                                                                                     by (term_dec . .)
or (eq T x x1) (eq T x x1)P:Prop.P
                                                                                  end of H_x0
                                                                                  (H26consider H_x0
                                                                                  we proceed by induction on H26 to prove sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) t2 x4))
                                                                                     case or_introl : H27:eq T x x1 
                                                                                        the thesis becomes sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) t2 x4))
                                                                                           (H28
                                                                                              by (eq_ind_r . . . H24 . H27)

                                                                                                 (eq
                                                                                                     T
                                                                                                     THead (Flat Appl) x (THead (Bind Abst) t2 x0)
                                                                                                     THead (Flat Appl) x (THead (Bind Abst) t2 x4))
                                                                                                   P:Prop.P
                                                                                           end of H28
                                                                                           we proceed by induction on H27 to prove sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) t2 x4))
                                                                                              case refl_equal : 
                                                                                                 the thesis becomes sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x4))
                                                                                                    (H_x1
                                                                                                       by (term_dec . .)
or (eq T x0 x4) (eq T x0 x4)P:Prop.P
                                                                                                    end of H_x1
                                                                                                    (H30consider H_x1
                                                                                                    we proceed by induction on H30 to prove sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x4))
                                                                                                       case or_introl : H31:eq T x0 x4 
                                                                                                          the thesis becomes sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x4))
                                                                                                             (H32
                                                                                                                by (eq_ind_r . . . H28 . H31)

                                                                                                                   (eq
                                                                                                                       T
                                                                                                                       THead (Flat Appl) x (THead (Bind Abst) t2 x0)
                                                                                                                       THead (Flat Appl) x (THead (Bind Abst) t2 x0))
                                                                                                                     P:Prop.P
                                                                                                             end of H32
                                                                                                             we proceed by induction on H31 to prove sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x4))
                                                                                                                case refl_equal : 
                                                                                                                   the thesis becomes sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x0))
                                                                                                                      by (refl_equal . .)
                                                                                                                      we proved 
                                                                                                                         eq
                                                                                                                           T
                                                                                                                           THead (Flat Appl) x (THead (Bind Abst) t2 x0)
                                                                                                                           THead (Flat Appl) x (THead (Bind Abst) t2 x0)
                                                                                                                      by (H32 previous .)
sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x0))
sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x4))
                                                                                                       case or_intror : H31:(eq T x0 x4)P:Prop.P 
                                                                                                          the thesis becomes sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x4))
                                                                                                             (h1
                                                                                                                 suppose H32eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                                                 assume PProp
                                                                                                                   (H33
                                                                                                                      by (f_equal . . . . . H32)
                                                                                                                      we proved 
                                                                                                                         eq
                                                                                                                           T
                                                                                                                           <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                                           <λ:T.T> CASE THead (Bind Abbr) x x4 OF TSort x0 | TLRef x0 | THead   t0t0

                                                                                                                         eq
                                                                                                                           T
                                                                                                                           λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                                             THead (Bind Abbr) x x0
                                                                                                                           λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                                             THead (Bind Abbr) x x4
                                                                                                                   end of H33
                                                                                                                   (H34
                                                                                                                      consider H33
                                                                                                                      we proved 
                                                                                                                         eq
                                                                                                                           T
                                                                                                                           <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                                           <λ:T.T> CASE THead (Bind Abbr) x x4 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                                      that is equivalent to eq T x0 x4
                                                                                                                      by (eq_ind_r . . . H31 . previous)
(eq T x0 x0)P0:Prop.P0
                                                                                                                   end of H34
                                                                                                                   by (refl_equal . .)
                                                                                                                   we proved eq T x0 x0
                                                                                                                   by (H34 previous .)
                                                                                                                   we proved P

                                                                                                                   eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                                                     P:Prop.P
                                                                                                             end of h1
                                                                                                             (h2
                                                                                                                by (H20 . .)
                                                                                                                we proved pr2 (CHead c (Bind Abbr) x) x0 x4
                                                                                                                by (pr2_head_2 . . . . . previous)
                                                                                                                we proved pr2 c (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                                                by (pr3_pr2 . . . previous)
pr3 c (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                                             end of h2
                                                                                                             (h3
                                                                                                                by (refl_equal . .)
eq T (THead (Bind Abbr) x x4) (THead (Bind Abbr) x x4)
                                                                                                             end of h3
                                                                                                             (h4by (sn3_sing . . H7) we proved sn3 c t2
                                                                                                             by (H5 . h1 h2 . . h3 . h4)
sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x4))
sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x4))
sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) t2 x4))
                                                                                     case or_intror : H27:(eq T x x1)P:Prop.P 
                                                                                        the thesis becomes sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) t2 x4))
                                                                                           (h1
                                                                                               suppose H28eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x1 x4)
                                                                                               assume PProp
                                                                                                 (H29
                                                                                                    by (f_equal . . . . . H28)
                                                                                                    we proved 
                                                                                                       eq
                                                                                                         T
                                                                                                         <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x | TLRef x | THead  t0 t0
                                                                                                         <λ:T.T> CASE THead (Bind Abbr) x1 x4 OF TSort x | TLRef x | THead  t0 t0

                                                                                                       eq
                                                                                                         T
                                                                                                         λe:T.<λ:T.T> CASE e OF TSort x | TLRef x | THead  t0 t0
                                                                                                           THead (Bind Abbr) x x0
                                                                                                         λe:T.<λ:T.T> CASE e OF TSort x | TLRef x | THead  t0 t0
                                                                                                           THead (Bind Abbr) x1 x4
                                                                                                 end of H29
                                                                                                 (h1
                                                                                                    (H30
                                                                                                       by (f_equal . . . . . H28)
                                                                                                       we proved 
                                                                                                          eq
                                                                                                            T
                                                                                                            <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                            <λ:T.T> CASE THead (Bind Abbr) x1 x4 OF TSort x0 | TLRef x0 | THead   t0t0

                                                                                                          eq
                                                                                                            T
                                                                                                            λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                              THead (Bind Abbr) x x0
                                                                                                            λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                              THead (Bind Abbr) x1 x4
                                                                                                    end of H30
                                                                                                    suppose H31eq T x x1
                                                                                                       (H33
                                                                                                          by (eq_ind_r . . . H27 . H31)
(eq T x x)P0:Prop.P0
                                                                                                       end of H33
                                                                                                       by (refl_equal . .)
                                                                                                       we proved eq T x x
                                                                                                       by (H33 previous .)
                                                                                                       we proved P
(eq T x x1)P
                                                                                                 end of h1
                                                                                                 (h2
                                                                                                    consider H29
                                                                                                    we proved 
                                                                                                       eq
                                                                                                         T
                                                                                                         <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x | TLRef x | THead  t0 t0
                                                                                                         <λ:T.T> CASE THead (Bind Abbr) x1 x4 OF TSort x | TLRef x | THead  t0 t0
eq T x x1
                                                                                                 end of h2
                                                                                                 by (h1 h2)
                                                                                                 we proved P

                                                                                                 eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x1 x4)
                                                                                                   P:Prop.P
                                                                                           end of h1
                                                                                           (h2
                                                                                              (h1by (pr3_pr2 . . . H14) we proved pr3 c x x1
                                                                                              (h2
                                                                                                 by (H20 . .)
                                                                                                 we proved pr2 (CHead c (Bind Abbr) x1) x0 x4
                                                                                                 by (pr3_pr2 . . . previous)
pr3 (CHead c (Bind Abbr) x1) x0 x4
                                                                                              end of h2
                                                                                              by (pr3_head_12 . . . h1 . . . h2)
pr3 c (THead (Bind Abbr) x x0) (THead (Bind Abbr) x1 x4)
                                                                                           end of h2
                                                                                           (h3
                                                                                              by (refl_equal . .)
eq T (THead (Bind Abbr) x1 x4) (THead (Bind Abbr) x1 x4)
                                                                                           end of h3
                                                                                           (h4by (sn3_sing . . H7) we proved sn3 c t2
                                                                                           by (H5 . h1 h2 . . h3 . h4)
sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) t2 x4))
sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) t2 x4))
sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                   case or_intror : H23:(eq T t2 x3)P:Prop.P 
                                                                      the thesis becomes sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                         (H_x0
                                                                            by (term_dec . .)
or (eq T x x1) (eq T x x1)P:Prop.P
                                                                         end of H_x0
                                                                         (H24consider H_x0
                                                                         we proceed by induction on H24 to prove sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                            case or_introl : H25:eq T x x1 
                                                                               the thesis becomes sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                                  we proceed by induction on H25 to prove sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                                     case refl_equal : 
                                                                                        the thesis becomes sn3 c (THead (Flat Appl) x (THead (Bind Abst) x3 x4))
                                                                                           (H_x1
                                                                                              by (term_dec . .)
or (eq T x0 x4) (eq T x0 x4)P:Prop.P
                                                                                           end of H_x1
                                                                                           (H27consider H_x1
                                                                                           we proceed by induction on H27 to prove sn3 c (THead (Flat Appl) x (THead (Bind Abst) x3 x4))
                                                                                              case or_introl : H28:eq T x0 x4 
                                                                                                 the thesis becomes sn3 c (THead (Flat Appl) x (THead (Bind Abst) x3 x4))
                                                                                                    we proceed by induction on H28 to prove sn3 c (THead (Flat Appl) x (THead (Bind Abst) x3 x4))
                                                                                                       case refl_equal : 
                                                                                                          the thesis becomes sn3 c (THead (Flat Appl) x (THead (Bind Abst) x3 x0))
                                                                                                             by (pr3_pr2 . . . H19)
                                                                                                             we proved pr3 c t2 x3
                                                                                                             by (H8 . H23 previous)
sn3 c (THead (Flat Appl) x (THead (Bind Abst) x3 x0))
sn3 c (THead (Flat Appl) x (THead (Bind Abst) x3 x4))
                                                                                              case or_intror : H28:(eq T x0 x4)P:Prop.P 
                                                                                                 the thesis becomes sn3 c (THead (Flat Appl) x (THead (Bind Abst) x3 x4))
                                                                                                    (h1
                                                                                                        suppose H29eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                                        assume PProp
                                                                                                          (H30
                                                                                                             by (f_equal . . . . . H29)
                                                                                                             we proved 
                                                                                                                eq
                                                                                                                  T
                                                                                                                  <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                                  <λ:T.T> CASE THead (Bind Abbr) x x4 OF TSort x0 | TLRef x0 | THead   t0t0

                                                                                                                eq
                                                                                                                  T
                                                                                                                  λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                                    THead (Bind Abbr) x x0
                                                                                                                  λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                                    THead (Bind Abbr) x x4
                                                                                                          end of H30
                                                                                                          (H31
                                                                                                             consider H30
                                                                                                             we proved 
                                                                                                                eq
                                                                                                                  T
                                                                                                                  <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                                  <λ:T.T> CASE THead (Bind Abbr) x x4 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                             that is equivalent to eq T x0 x4
                                                                                                             by (eq_ind_r . . . H28 . previous)
(eq T x0 x0)P0:Prop.P0
                                                                                                          end of H31
                                                                                                          by (refl_equal . .)
                                                                                                          we proved eq T x0 x0
                                                                                                          by (H31 previous .)
                                                                                                          we proved P

                                                                                                          eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                                            P:Prop.P
                                                                                                    end of h1
                                                                                                    (h2
                                                                                                       by (H20 . .)
                                                                                                       we proved pr2 (CHead c (Bind Abbr) x) x0 x4
                                                                                                       by (pr2_head_2 . . . . . previous)
                                                                                                       we proved pr2 c (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                                       by (pr3_pr2 . . . previous)
pr3 c (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                                    end of h2
                                                                                                    (h3
                                                                                                       by (refl_equal . .)
eq T (THead (Bind Abbr) x x4) (THead (Bind Abbr) x x4)
                                                                                                    end of h3
                                                                                                    (h4
                                                                                                       by (pr3_pr2 . . . H19)
                                                                                                       we proved pr3 c t2 x3
                                                                                                       by (H7 . H23 previous)
sn3 c x3
                                                                                                    end of h4
                                                                                                    by (H5 . h1 h2 . . h3 . h4)
sn3 c (THead (Flat Appl) x (THead (Bind Abst) x3 x4))
sn3 c (THead (Flat Appl) x (THead (Bind Abst) x3 x4))
sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                            case or_intror : H25:(eq T x x1)P:Prop.P 
                                                                               the thesis becomes sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                                  (h1
                                                                                      suppose H26eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x1 x4)
                                                                                      assume PProp
                                                                                        (H27
                                                                                           by (f_equal . . . . . H26)
                                                                                           we proved 
                                                                                              eq
                                                                                                T
                                                                                                <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x | TLRef x | THead  t0 t0
                                                                                                <λ:T.T> CASE THead (Bind Abbr) x1 x4 OF TSort x | TLRef x | THead  t0 t0

                                                                                              eq
                                                                                                T
                                                                                                λe:T.<λ:T.T> CASE e OF TSort x | TLRef x | THead  t0 t0
                                                                                                  THead (Bind Abbr) x x0
                                                                                                λe:T.<λ:T.T> CASE e OF TSort x | TLRef x | THead  t0 t0
                                                                                                  THead (Bind Abbr) x1 x4
                                                                                        end of H27
                                                                                        (h1
                                                                                           (H28
                                                                                              by (f_equal . . . . . H26)
                                                                                              we proved 
                                                                                                 eq
                                                                                                   T
                                                                                                   <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                   <λ:T.T> CASE THead (Bind Abbr) x1 x4 OF TSort x0 | TLRef x0 | THead   t0t0

                                                                                                 eq
                                                                                                   T
                                                                                                   λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                     THead (Bind Abbr) x x0
                                                                                                   λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                     THead (Bind Abbr) x1 x4
                                                                                           end of H28
                                                                                           suppose H29eq T x x1
                                                                                              (H31
                                                                                                 by (eq_ind_r . . . H25 . H29)
(eq T x x)P0:Prop.P0
                                                                                              end of H31
                                                                                              by (refl_equal . .)
                                                                                              we proved eq T x x
                                                                                              by (H31 previous .)
                                                                                              we proved P
(eq T x x1)P
                                                                                        end of h1
                                                                                        (h2
                                                                                           consider H27
                                                                                           we proved 
                                                                                              eq
                                                                                                T
                                                                                                <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x | TLRef x | THead  t0 t0
                                                                                                <λ:T.T> CASE THead (Bind Abbr) x1 x4 OF TSort x | TLRef x | THead  t0 t0
eq T x x1
                                                                                        end of h2
                                                                                        by (h1 h2)
                                                                                        we proved P

                                                                                        eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x1 x4)
                                                                                          P:Prop.P
                                                                                  end of h1
                                                                                  (h2
                                                                                     (h1by (pr3_pr2 . . . H14) we proved pr3 c x x1
                                                                                     (h2
                                                                                        by (H20 . .)
                                                                                        we proved pr2 (CHead c (Bind Abbr) x1) x0 x4
                                                                                        by (pr3_pr2 . . . previous)
pr3 (CHead c (Bind Abbr) x1) x0 x4
                                                                                     end of h2
                                                                                     by (pr3_head_12 . . . h1 . . . h2)
pr3 c (THead (Bind Abbr) x x0) (THead (Bind Abbr) x1 x4)
                                                                                  end of h2
                                                                                  (h3
                                                                                     by (refl_equal . .)
eq T (THead (Bind Abbr) x1 x4) (THead (Bind Abbr) x1 x4)
                                                                                  end of h3
                                                                                  (h4
                                                                                     by (pr3_pr2 . . . H19)
                                                                                     we proved pr3 c t2 x3
                                                                                     by (H7 . H23 previous)
sn3 c x3
                                                                                  end of h4
                                                                                  by (H5 . h1 h2 . . h3 . h4)
sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                we proved sn3 c (THead (Flat Appl) x1 (THead (Bind Abst) x3 x4))
                                                                by (eq_ind_r . . . previous . H18)
sn3 c (THead (Flat Appl) x1 x2)
                                                       we proved sn3 c (THead (Flat Appl) x1 x2)
                                                       by (eq_ind_r . . . previous . H13)
sn3 c t3
sn3 c t3
                                        case or3_intro1 : H12:ex4_4 T T T T λy1:T.λz1:T.λ:T.λ:T.eq T (THead (Bind Abst) t2 x0) (THead (Bind Abst) y1 z1) λ:T.λ:T.λu2:T.λt4:T.eq T t3 (THead (Bind Abbr) u2 t4) λ:T.λ:T.λu2:T.λ:T.pr2 c x u2 λ:T.λz1:T.λ:T.λt4:T.b:B.u:T.(pr2 (CHead c (Bind b) u) z1 t4) 
                                           the thesis becomes sn3 c t3
                                              we proceed by induction on H12 to prove sn3 c t3
                                                 case ex4_4_intro : x1:T x2:T x3:T x4:T H13:eq T (THead (Bind Abst) t2 x0) (THead (Bind Abst) x1 x2) H14:eq T t3 (THead (Bind Abbr) x3 x4) H15:pr2 c x x3 H16:b:B.u:T.(pr2 (CHead c (Bind b) u) x2 x4) 
                                                    the thesis becomes sn3 c t3
                                                       (H18
                                                          by (f_equal . . . . . H13)
                                                          we proved 
                                                             eq
                                                               T
                                                               <λ:T.T> CASE THead (Bind Abst) t2 x0 OF TSort t2 | TLRef t2 | THead  t0 t0
                                                               <λ:T.T> CASE THead (Bind Abst) x1 x2 OF TSort t2 | TLRef t2 | THead  t0 t0

                                                             eq
                                                               T
                                                               λe:T.<λ:T.T> CASE e OF TSort t2 | TLRef t2 | THead  t0 t0
                                                                 THead (Bind Abst) t2 x0
                                                               λe:T.<λ:T.T> CASE e OF TSort t2 | TLRef t2 | THead  t0 t0
                                                                 THead (Bind Abst) x1 x2
                                                       end of H18
                                                       (h1
                                                          (H19
                                                             by (f_equal . . . . . H13)
                                                             we proved 
                                                                eq
                                                                  T
                                                                  <λ:T.T> CASE THead (Bind Abst) t2 x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                  <λ:T.T> CASE THead (Bind Abst) x1 x2 OF TSort x0 | TLRef x0 | THead   t0t0

                                                                eq
                                                                  T
                                                                  λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                    THead (Bind Abst) t2 x0
                                                                  λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                    THead (Bind Abst) x1 x2
                                                          end of H19
                                                          suppose eq T t2 x1
                                                             (H21
                                                                consider H19
                                                                we proved 
                                                                   eq
                                                                     T
                                                                     <λ:T.T> CASE THead (Bind Abst) t2 x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                     <λ:T.T> CASE THead (Bind Abst) x1 x2 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                that is equivalent to eq T x0 x2
                                                                by (eq_ind_r . . . H16 . previous)
b:B.u:T.(pr2 (CHead c (Bind b) u) x0 x4)
                                                             end of H21
                                                             (H_x
                                                                by (term_dec . .)
or (eq T x x3) (eq T x x3)P:Prop.P
                                                             end of H_x
                                                             (H22consider H_x
                                                             we proceed by induction on H22 to prove sn3 c (THead (Bind Abbr) x3 x4)
                                                                case or_introl : H23:eq T x x3 
                                                                   the thesis becomes sn3 c (THead (Bind Abbr) x3 x4)
                                                                      we proceed by induction on H23 to prove sn3 c (THead (Bind Abbr) x3 x4)
                                                                         case refl_equal : 
                                                                            the thesis becomes sn3 c (THead (Bind Abbr) x x4)
                                                                               (H_x0
                                                                                  by (term_dec . .)
or (eq T x0 x4) (eq T x0 x4)P:Prop.P
                                                                               end of H_x0
                                                                               (H25consider H_x0
                                                                               we proceed by induction on H25 to prove sn3 c (THead (Bind Abbr) x x4)
                                                                                  case or_introl : H26:eq T x0 x4 
                                                                                     the thesis becomes sn3 c (THead (Bind Abbr) x x4)
                                                                                        we proceed by induction on H26 to prove sn3 c (THead (Bind Abbr) x x4)
                                                                                           case refl_equal : 
                                                                                              the thesis becomes sn3 c (THead (Bind Abbr) x x0)
                                                                                                 by (sn3_sing . . H6)
sn3 c (THead (Bind Abbr) x x0)
sn3 c (THead (Bind Abbr) x x4)
                                                                                  case or_intror : H26:(eq T x0 x4)P:Prop.P 
                                                                                     the thesis becomes sn3 c (THead (Bind Abbr) x x4)
                                                                                        (h1
                                                                                            suppose H27eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                            assume PProp
                                                                                              (H28
                                                                                                 by (f_equal . . . . . H27)
                                                                                                 we proved 
                                                                                                    eq
                                                                                                      T
                                                                                                      <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                      <λ:T.T> CASE THead (Bind Abbr) x x4 OF TSort x0 | TLRef x0 | THead   t0t0

                                                                                                    eq
                                                                                                      T
                                                                                                      λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                        THead (Bind Abbr) x x0
                                                                                                      λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                        THead (Bind Abbr) x x4
                                                                                              end of H28
                                                                                              (H29
                                                                                                 consider H28
                                                                                                 we proved 
                                                                                                    eq
                                                                                                      T
                                                                                                      <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                      <λ:T.T> CASE THead (Bind Abbr) x x4 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                                 that is equivalent to eq T x0 x4
                                                                                                 by (eq_ind_r . . . H26 . previous)
(eq T x0 x0)P0:Prop.P0
                                                                                              end of H29
                                                                                              by (refl_equal . .)
                                                                                              we proved eq T x0 x0
                                                                                              by (H29 previous .)
                                                                                              we proved P

                                                                                              eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                                P:Prop.P
                                                                                        end of h1
                                                                                        (h2
                                                                                           by (H21 . .)
                                                                                           we proved pr2 (CHead c (Bind Abbr) x) x0 x4
                                                                                           by (pr2_head_2 . . . . . previous)
                                                                                           we proved pr2 c (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                           by (pr3_pr2 . . . previous)
pr3 c (THead (Bind Abbr) x x0) (THead (Bind Abbr) x x4)
                                                                                        end of h2
                                                                                        by (H6 . h1 h2)
sn3 c (THead (Bind Abbr) x x4)
sn3 c (THead (Bind Abbr) x x4)
sn3 c (THead (Bind Abbr) x3 x4)
                                                                case or_intror : H23:(eq T x x3)P:Prop.P 
                                                                   the thesis becomes sn3 c (THead (Bind Abbr) x3 x4)
                                                                      (h1
                                                                          suppose H24eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x3 x4)
                                                                          assume PProp
                                                                            (H25
                                                                               by (f_equal . . . . . H24)
                                                                               we proved 
                                                                                  eq
                                                                                    T
                                                                                    <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x | TLRef x | THead  t0 t0
                                                                                    <λ:T.T> CASE THead (Bind Abbr) x3 x4 OF TSort x | TLRef x | THead  t0 t0

                                                                                  eq
                                                                                    T
                                                                                    λe:T.<λ:T.T> CASE e OF TSort x | TLRef x | THead  t0 t0
                                                                                      THead (Bind Abbr) x x0
                                                                                    λe:T.<λ:T.T> CASE e OF TSort x | TLRef x | THead  t0 t0
                                                                                      THead (Bind Abbr) x3 x4
                                                                            end of H25
                                                                            (h1
                                                                               (H26
                                                                                  by (f_equal . . . . . H24)
                                                                                  we proved 
                                                                                     eq
                                                                                       T
                                                                                       <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                       <λ:T.T> CASE THead (Bind Abbr) x3 x4 OF TSort x0 | TLRef x0 | THead   t0t0

                                                                                     eq
                                                                                       T
                                                                                       λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                         THead (Bind Abbr) x x0
                                                                                       λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                                         THead (Bind Abbr) x3 x4
                                                                               end of H26
                                                                               suppose H27eq T x x3
                                                                                  (H29
                                                                                     by (eq_ind_r . . . H23 . H27)
(eq T x x)P0:Prop.P0
                                                                                  end of H29
                                                                                  by (refl_equal . .)
                                                                                  we proved eq T x x
                                                                                  by (H29 previous .)
                                                                                  we proved P
(eq T x x3)P
                                                                            end of h1
                                                                            (h2
                                                                               consider H25
                                                                               we proved 
                                                                                  eq
                                                                                    T
                                                                                    <λ:T.T> CASE THead (Bind Abbr) x x0 OF TSort x | TLRef x | THead  t0 t0
                                                                                    <λ:T.T> CASE THead (Bind Abbr) x3 x4 OF TSort x | TLRef x | THead  t0 t0
eq T x x3
                                                                            end of h2
                                                                            by (h1 h2)
                                                                            we proved P

                                                                            eq T (THead (Bind Abbr) x x0) (THead (Bind Abbr) x3 x4)
                                                                              P:Prop.P
                                                                      end of h1
                                                                      (h2
                                                                         (h1by (pr3_pr2 . . . H15) we proved pr3 c x x3
                                                                         (h2
                                                                            by (H21 . .)
                                                                            we proved pr2 (CHead c (Bind Abbr) x3) x0 x4
                                                                            by (pr3_pr2 . . . previous)
pr3 (CHead c (Bind Abbr) x3) x0 x4
                                                                         end of h2
                                                                         by (pr3_head_12 . . . h1 . . . h2)
pr3 c (THead (Bind Abbr) x x0) (THead (Bind Abbr) x3 x4)
                                                                      end of h2
                                                                      by (H6 . h1 h2)
sn3 c (THead (Bind Abbr) x3 x4)
                                                             we proved sn3 c (THead (Bind Abbr) x3 x4)
(eq T t2 x1)(sn3 c (THead (Bind Abbr) x3 x4))
                                                       end of h1
                                                       (h2
                                                          consider H18
                                                          we proved 
                                                             eq
                                                               T
                                                               <λ:T.T> CASE THead (Bind Abst) t2 x0 OF TSort t2 | TLRef t2 | THead  t0 t0
                                                               <λ:T.T> CASE THead (Bind Abst) x1 x2 OF TSort t2 | TLRef t2 | THead  t0 t0
eq T t2 x1
                                                       end of h2
                                                       by (h1 h2)
                                                       we proved sn3 c (THead (Bind Abbr) x3 x4)
                                                       by (eq_ind_r . . . previous . H14)
sn3 c t3
sn3 c t3
                                        case or3_intro2 : H12:ex6_6 B T T T T T λb:B.λ:T.λ:T.λ:T.λ:T.λ:T.not (eq B b Abstλb:B.λy1:T.λz1:T.λ:T.λ:T.λ:T.eq T (THead (Bind Abst) t2 x0) (THead (Bind b) y1 z1) λb:B.λ:T.λ:T.λz2:T.λu2:T.λy2:T.eq T t3 (THead (Bind b) y2 (THead (Flat Appl) (lift (S OO u2) z2)) λ:B.λ:T.λ:T.λ:T.λu2:T.λ:T.pr2 c x u2 λ:B.λy1:T.λ:T.λ:T.λ:T.λy2:T.pr2 c y1 y2 λb:B.λ:T.λz1:T.λz2:T.λ:T.λy2:T.pr2 (CHead c (Bind b) y2) z1 z2 
                                           the thesis becomes sn3 c t3
                                              we proceed by induction on H12 to prove sn3 c t3
                                                 case ex6_6_intro : x1:B x2:T x3:T x4:T x5:T x6:T H13:not (eq B x1 Abst) H14:eq T (THead (Bind Abst) t2 x0) (THead (Bind x1) x2 x3) H15:eq T t3 (THead (Bind x1) x6 (THead (Flat Appl) (lift (S OO x5) x4)) :pr2 c x x5 H17:pr2 c x2 x6 H18:pr2 (CHead c (Bind x1) x6) x3 x4 
                                                    the thesis becomes sn3 c t3
                                                       (H20
                                                          by (f_equal . . . . . H14)
                                                          we proved 
                                                             eq
                                                               B
                                                               <λ:T.B>
                                                                 CASE THead (Bind Abst) t2 x0 OF
                                                                   TSort Abst
                                                                 | TLRef Abst
                                                                 | THead k  <λ:K.B> CASE k OF Bind bb | Flat Abst
                                                               <λ:T.B>
                                                                 CASE THead (Bind x1) x2 x3 OF
                                                                   TSort Abst
                                                                 | TLRef Abst
                                                                 | THead k  <λ:K.B> CASE k OF Bind bb | 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 bb | Flat Abst
                                                                 THead (Bind Abst) t2 x0
                                                               λe:T
                                                                   .<λ:T.B>
                                                                     CASE e OF
                                                                       TSort Abst
                                                                     | TLRef Abst
                                                                     | THead k  <λ:K.B> CASE k OF Bind bb | Flat Abst
                                                                 THead (Bind x1) x2 x3
                                                       end of H20
                                                       (h1
                                                          (H21
                                                             by (f_equal . . . . . H14)
                                                             we proved 
                                                                eq
                                                                  T
                                                                  <λ:T.T> CASE THead (Bind Abst) t2 x0 OF TSort t2 | TLRef t2 | THead  t0 t0
                                                                  <λ:T.T> CASE THead (Bind x1) x2 x3 OF TSort t2 | TLRef t2 | THead  t0 t0

                                                                eq
                                                                  T
                                                                  λe:T.<λ:T.T> CASE e OF TSort t2 | TLRef t2 | THead  t0 t0
                                                                    THead (Bind Abst) t2 x0
                                                                  λe:T.<λ:T.T> CASE e OF TSort t2 | TLRef t2 | THead  t0 t0 (THead (Bind x1) x2 x3)
                                                          end of H21
                                                          (h1
                                                             (H22
                                                                by (f_equal . . . . . H14)
                                                                we proved 
                                                                   eq
                                                                     T
                                                                     <λ:T.T> CASE THead (Bind Abst) t2 x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                     <λ:T.T> CASE THead (Bind x1) x2 x3 OF TSort x0 | TLRef x0 | THead   t0t0

                                                                   eq
                                                                     T
                                                                     λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0
                                                                       THead (Bind Abst) t2 x0
                                                                     λe:T.<λ:T.T> CASE e OF TSort x0 | TLRef x0 | THead   t0t0 (THead (Bind x1) x2 x3)
                                                             end of H22
                                                              suppose H23eq T t2 x2
                                                              suppose H24eq B Abst x1
                                                                (H25
                                                                   consider H22
                                                                   we proved 
                                                                      eq
                                                                        T
                                                                        <λ:T.T> CASE THead (Bind Abst) t2 x0 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                        <λ:T.T> CASE THead (Bind x1) x2 x3 OF TSort x0 | TLRef x0 | THead   t0t0
                                                                   that is equivalent to eq T x0 x3
                                                                   by (eq_ind_r . . . H18 . previous)
pr2 (CHead c (Bind x1) x6) x0 x4
                                                                end of H25
                                                                (H28
                                                                   by (eq_ind_r . . . H13 . H24)
not (eq B Abst Abst)
                                                                end of H28
                                                                we proceed by induction on H24 to prove sn3 c (THead (Bind x1) x6 (THead (Flat Appl) (lift (S OO x5) x4))
                                                                   case refl_equal : 
                                                                      the thesis becomes 
                                                                      sn3 c (THead (Bind Abst) x6 (THead (Flat Appl) (lift (S OO x5) x4))
                                                                         (H29
                                                                            by (refl_equal . .)
                                                                            we proved eq B Abst Abst
                                                                            by (H28 previous)
                                                                            we proved False
                                                                            by cases on the previous result we prove 
                                                                               sn3 c (THead (Bind Abst) x6 (THead (Flat Appl) (lift (S OO x5) x4))

                                                                               sn3 c (THead (Bind Abst) x6 (THead (Flat Appl) (lift (S OO x5) x4))
                                                                         end of H29
                                                                         consider H29

                                                                            sn3 c (THead (Bind Abst) x6 (THead (Flat Appl) (lift (S OO x5) x4))
                                                                we proved sn3 c (THead (Bind x1) x6 (THead (Flat Appl) (lift (S OO x5) x4))

                                                                eq T t2 x2
                                                                  (eq B Abst x1
                                                                       sn3 c (THead (Bind x1) x6 (THead (Flat Appl) (lift (S OO x5) x4)))
                                                          end of h1
                                                          (h2
                                                             consider H21
                                                             we proved 
                                                                eq
                                                                  T
                                                                  <λ:T.T> CASE THead (Bind Abst) t2 x0 OF TSort t2 | TLRef t2 | THead  t0 t0
                                                                  <λ:T.T> CASE THead (Bind x1) x2 x3 OF TSort t2 | TLRef t2 | THead  t0 t0
eq T t2 x2
                                                          end of h2
                                                          by (h1 h2)

                                                             eq B Abst x1
                                                               sn3 c (THead (Bind x1) x6 (THead (Flat Appl) (lift (S OO x5) x4))
                                                       end of h1
                                                       (h2
                                                          consider H20
                                                          we proved 
                                                             eq
                                                               B
                                                               <λ:T.B>
                                                                 CASE THead (Bind Abst) t2 x0 OF
                                                                   TSort Abst
                                                                 | TLRef Abst
                                                                 | THead k  <λ:K.B> CASE k OF Bind bb | Flat Abst
                                                               <λ:T.B>
                                                                 CASE THead (Bind x1) x2 x3 OF
                                                                   TSort Abst
                                                                 | TLRef Abst
                                                                 | THead k  <λ:K.B> CASE k OF Bind bb | Flat Abst
eq B Abst x1
                                                       end of h2
                                                       by (h1 h2)
                                                       we proved sn3 c (THead (Bind x1) x6 (THead (Flat Appl) (lift (S OO x5) x4))
                                                       by (eq_ind_r . . . previous . H15)
sn3 c t3
sn3 c t3
                                     we proved sn3 c t3
                                  we proved 
                                     t3:T
                                       .eq T (THead (Flat Appl) x (THead (Bind Abst) t2 x0)) t3
                                           P:Prop.P
                                         (pr2 c (THead (Flat Appl) x (THead (Bind Abst) t2 x0)) t3)(sn3 c t3)
                                  by (sn3_pr2_intro . . previous)
sn3 c (THead (Flat Appl) x (THead (Bind Abst) t2 x0))
                         we proved sn3 c (THead (Flat Appl) x (THead (Bind Abst) w x0))

                         x:T
                           .x0:T
                             .H3:eq T t1 (THead (Bind Abbr) x x0)
                               .w:T.H4:(sn3 c w).(sn3 c (THead (Flat Appl) x (THead (Bind Abst) w x0)))
             we proved 
                x:T
                  .x0:T
                    .eq T y (THead (Bind Abbr) x x0)
                      w:T
                           .(sn3 c w)(sn3 c (THead (Flat Appl) x (THead (Bind Abst) w x0)))
             by (unintro . . . previous)
             we proved 
                x:T
                  .eq T y (THead (Bind Abbr) v x)
                    w:T
                         .(sn3 c w)(sn3 c (THead (Flat Appl) v (THead (Bind Abst) w x)))
             by (unintro . . . previous)
             we proved 
                eq T y (THead (Bind Abbr) v t)
                  w:T
                       .(sn3 c w)(sn3 c (THead (Flat Appl) v (THead (Bind Abst) w t)))
          we proved 
             y:T
               .sn3 c y
                 (eq T y (THead (Bind Abbr) v t)
                      w:T
                           .(sn3 c w)(sn3 c (THead (Flat Appl) v (THead (Bind Abst) w t))))
          by (insert_eq . . . . previous H)
          we proved 
             w:T
               .(sn3 c w)(sn3 c (THead (Flat Appl) v (THead (Bind Abst) w t)))
       we proved 
          c:C
            .v:T
              .t:T
                .sn3 c (THead (Bind Abbr) v t)
                  w:T
                       .(sn3 c w)(sn3 c (THead (Flat Appl) v (THead (Bind Abst) w t)))