DEFINITION drop_conf_lt()
TYPE =
       k:K
         .i:nat
           .u:T
             .c0:C
               .c:C
                 .drop i O c (CHead c0 k u)
                   e:C
                        .h:nat
                          .d:nat
                            .drop h (S (plus i d)) c e
                              (ex3_2
                                   T
                                   C
                                   λv:T.λ:C.eq T u (lift h (r k d) v)
                                   λv:T.λe0:C.drop i O e (CHead e0 k v)
                                   λ:T.λe0:C.drop h (r k d) c0 e0)
BODY =
        assume kK
        assume inat
          we proceed by induction on i to prove 
             u:T
               .c0:C
                 .c:C
                   .drop i O c (CHead c0 k u)
                     e:C
                          .h:nat
                            .d:nat
                              .drop h (S (plus i d)) c e
                                (ex3_2
                                     T
                                     C
                                     λv:T.λ:C.eq T u (lift h (r k d) v)
                                     λv:T.λe0:C.drop i O e (CHead e0 k v)
                                     λ:T.λe0:C.drop h (r k d) c0 e0)
             case O : 
                the thesis becomes 
                u:T
                  .c0:C
                    .c:C
                      .drop O O c (CHead c0 k u)
                        e:C
                             .h:nat
                               .d:nat
                                 .drop h (S (plus O d)) c e
                                   (ex3_2
                                        T
                                        C
                                        λv:T.λ:C.eq T u (lift h (r k d) v)
                                        λv:T.λe0:C.drop O O e (CHead e0 k v)
                                        λ:T.λe0:C.drop h (r k d) c0 e0)
                    assume uT
                    assume c0C
                    assume cC
                    suppose Hdrop O O c (CHead c0 k u)
                    assume eC
                    assume hnat
                    assume dnat
                    suppose H0drop h (S (plus O d)) c e
                      (H1
                         by (drop_gen_refl . . H)
                         we proved eq C c (CHead c0 k u)
                         we proceed by induction on the previous result to prove drop h (S (plus O d)) (CHead c0 k u) e
                            case refl_equal : 
                               the thesis becomes the hypothesis H0
drop h (S (plus O d)) (CHead c0 k u) e
                      end of H1
                      by (drop_gen_skip_l . . . . . . H1)
                      we proved 
                         ex3_2
                           C
                           T
                           λe:C.λv:T.eq C e (CHead e k v)
                           λ:C.λv:T.eq T u (lift h (r k (plus O d)) v)
                           λe:C.λ:T.drop h (r k (plus O d)) c0 e
                      we proceed by induction on the previous result to prove 
                         ex3_2
                           T
                           C
                           λv:T.λ:C.eq T u (lift h (r k d) v)
                           λv:T.λe0:C.drop O O e (CHead e0 k v)
                           λ:T.λe0:C.drop h (r k d) c0 e0
                         case ex3_2_intro : x0:C x1:T H2:eq C e (CHead x0 k x1) H3:eq T u (lift h (r k (plus O d)) x1) H4:drop h (r k (plus O d)) c0 x0 
                            the thesis becomes 
                            ex3_2
                              T
                              C
                              λv:T.λ:C.eq T u (lift h (r k d) v)
                              λv:T.λe0:C.drop O O e (CHead e0 k v)
                              λ:T.λe0:C.drop h (r k d) c0 e0
                               (h1
                                  by (refl_equal . .)
                                  we proved eq T (lift h (r k d) x1) (lift h (r k d) x1)
eq T (lift h (r k (plus O d)) x1) (lift h (r k d) x1)
                               end of h1
                               (h2
                                  by (drop_refl .)
drop O O (CHead x0 k x1) (CHead x0 k x1)
                               end of h2
                               (h3
                                  consider H4
                                  we proved drop h (r k (plus O d)) c0 x0
drop h (r k d) c0 x0
                               end of h3
                               by (ex3_2_intro . . . . . . . h1 h2 h3)
                               we proved 
                                  ex3_2
                                    T
                                    C
                                    λv:T.λ:C.eq T (lift h (r k (plus O d)) x1) (lift h (r k d) v)
                                    λv:T.λe0:C.drop O O (CHead x0 k x1) (CHead e0 k v)
                                    λ:T.λe0:C.drop h (r k d) c0 e0
                               by (eq_ind_r . . . previous . H3)
                               we proved 
                                  ex3_2
                                    T
                                    C
                                    λv:T.λ:C.eq T u (lift h (r k d) v)
                                    λv:T.λe0:C.drop O O (CHead x0 k x1) (CHead e0 k v)
                                    λ:T.λe0:C.drop h (r k d) c0 e0
                               by (eq_ind_r . . . previous . H2)

                                  ex3_2
                                    T
                                    C
                                    λv:T.λ:C.eq T u (lift h (r k d) v)
                                    λv:T.λe0:C.drop O O e (CHead e0 k v)
                                    λ:T.λe0:C.drop h (r k d) c0 e0
                      we proved 
                         ex3_2
                           T
                           C
                           λv:T.λ:C.eq T u (lift h (r k d) v)
                           λv:T.λe0:C.drop O O e (CHead e0 k v)
                           λ:T.λe0:C.drop h (r k d) c0 e0

                      u:T
                        .c0:C
                          .c:C
                            .drop O O c (CHead c0 k u)
                              e:C
                                   .h:nat
                                     .d:nat
                                       .drop h (S (plus O d)) c e
                                         (ex3_2
                                              T
                                              C
                                              λv:T.λ:C.eq T u (lift h (r k d) v)
                                              λv:T.λe0:C.drop O O e (CHead e0 k v)
                                              λ:T.λe0:C.drop h (r k d) c0 e0)
             case S : i0:nat 
                the thesis becomes 
                u:T
                  .c0:C
                    .c:C
                      .drop (S i0) O c (CHead c0 k u)
                        e:C
                             .h:nat
                               .d:nat
                                 .drop h (S (plus (S i0) d)) c e
                                   (ex3_2
                                        T
                                        C
                                        λv:T.λ:C.eq T u (lift h (r k d) v)
                                        λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                        λ:T.λe0:C.drop h (r k d) c0 e0)
                (H) by induction hypothesis we know 
                   u:T
                     .c0:C
                       .c:C
                         .drop i0 O c (CHead c0 k u)
                           e:C
                                .h:nat
                                  .d:nat
                                    .drop h (S (plus i0 d)) c e
                                      (ex3_2
                                           T
                                           C
                                           λv:T.λ:C.eq T u (lift h (r k d) v)
                                           λv:T.λe0:C.drop i0 O e (CHead e0 k v)
                                           λ:T.λe0:C.drop h (r k d) c0 e0)
                    assume uT
                    assume c0C
                    assume cC
                      we proceed by induction on c to prove 
                         drop (S i0) O c (CHead c0 k u)
                           e:C
                                .h:nat
                                  .d:nat
                                    .drop h (S (plus (S i0) d)) c e
                                      (ex3_2
                                           T
                                           C
                                           λv:T.λ:C.eq T u (lift h (r k d) v)
                                           λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                           λ:T.λe0:C.drop h (r k d) c0 e0)
                         case CSort : n:nat 
                            the thesis becomes 
                            drop (S i0) O (CSort n) (CHead c0 k u)
                              e:C
                                   .h:nat
                                     .d:nat
                                       .H1:drop h (S (plus (S i0) d)) (CSort n) e
                                         .ex3_2
                                           T
                                           C
                                           λv:T.λ:C.eq T u (lift h (r k d) v)
                                           λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                           λ:T.λe0:C.drop h (r k d) c0 e0
                                suppose drop (S i0) O (CSort n) (CHead c0 k u)
                                assume eC
                                assume hnat
                                assume dnat
                                suppose H1drop h (S (plus (S i0) d)) (CSort n) e
                                  by (drop_gen_sort . . . . H1)
                                  we proved and3 (eq C e (CSort n)) (eq nat h O) (eq nat (S (plus (S i0) d)) O)
                                  we proceed by induction on the previous result to prove 
                                     ex3_2
                                       T
                                       C
                                       λv:T.λ:C.eq T u (lift h (r k d) v)
                                       λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                       λ:T.λe0:C.drop h (r k d) c0 e0
                                     case and3_intro : :eq C e (CSort n) :eq nat h O H4:eq nat (S (plus (S i0) d)) O 
                                        the thesis becomes 
                                        ex3_2
                                          T
                                          C
                                          λv:T.λ:C.eq T u (lift h (r k d) v)
                                          λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                          λ:T.λe0:C.drop h (r k d) c0 e0
                                           (H5
                                              we proceed by induction on H4 to prove <λ:nat.Prop> CASE O OF OFalse | S True
                                                 case refl_equal : 
                                                    the thesis becomes <λ:nat.Prop> CASE S (plus (S i0) d) OF OFalse | S True
                                                       consider I
                                                       we proved True
<λ:nat.Prop> CASE S (plus (S i0) d) OF OFalse | S True
<λ:nat.Prop> CASE O OF OFalse | S True
                                           end of H5
                                           consider H5
                                           we proved <λ:nat.Prop> CASE O OF OFalse | S True
                                           that is equivalent to False
                                           we proceed by induction on the previous result to prove 
                                              ex3_2
                                                T
                                                C
                                                λv:T.λ:C.eq T u (lift h (r k d) v)
                                                λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                λ:T.λe0:C.drop h (r k d) c0 e0

                                              ex3_2
                                                T
                                                C
                                                λv:T.λ:C.eq T u (lift h (r k d) v)
                                                λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                λ:T.λe0:C.drop h (r k d) c0 e0
                                  we proved 
                                     ex3_2
                                       T
                                       C
                                       λv:T.λ:C.eq T u (lift h (r k d) v)
                                       λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                       λ:T.λe0:C.drop h (r k d) c0 e0

                                  drop (S i0) O (CSort n) (CHead c0 k u)
                                    e:C
                                         .h:nat
                                           .d:nat
                                             .H1:drop h (S (plus (S i0) d)) (CSort n) e
                                               .ex3_2
                                                 T
                                                 C
                                                 λv:T.λ:C.eq T u (lift h (r k d) v)
                                                 λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                 λ:T.λe0:C.drop h (r k d) c0 e0
                         case CHead 
                            we need to prove 
                            c1:C
                              .drop (S i0) O c1 (CHead c0 k u)
                                  e:C
                                       .h:nat
                                         .d:nat
                                           .drop h (S (plus (S i0) d)) c1 e
                                             (ex3_2
                                                  T
                                                  C
                                                  λv:T.λ:C.eq T u (lift h (r k d) v)
                                                  λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                  λ:T.λe0:C.drop h (r k d) c0 e0)
                                k0:K
                                     .t:T
                                       .drop (S i0) O (CHead c1 k0 t) (CHead c0 k u)
                                         e:C
                                              .h:nat
                                                .d:nat
                                                  .drop h (S (plus (S i0) d)) (CHead c1 k0 t) e
                                                    (ex3_2
                                                         T
                                                         C
                                                         λv:T.λ:C.eq T u (lift h (r k d) v)
                                                         λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                         λ:T.λe0:C.drop h (r k d) c0 e0)
                                assume c1C
                                suppose H0
                                   drop (S i0) O c1 (CHead c0 k u)
                                     e:C
                                          .h:nat
                                            .d:nat
                                              .drop h (S (plus (S i0) d)) c1 e
                                                (ex3_2
                                                     T
                                                     C
                                                     λv:T.λ:C.eq T u (lift h (r k d) v)
                                                     λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                     λ:T.λe0:C.drop h (r k d) c0 e0)
                                assume k0K
                                  we proceed by induction on k0 to prove 
                                     t:T
                                       .drop (S i0) O (CHead c1 k0 t) (CHead c0 k u)
                                         e:C
                                              .h:nat
                                                .d:nat
                                                  .drop h (S (plus (S i0) d)) (CHead c1 k0 t) e
                                                    (ex3_2
                                                         T
                                                         C
                                                         λv:T.λ:C.eq T u (lift h (r k d) v)
                                                         λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                         λ:T.λe0:C.drop h (r k d) c0 e0)
                                     case Bind : b:B 
                                        the thesis becomes 
                                        t:T
                                          .H1:drop (S i0) O (CHead c1 (Bind b) t) (CHead c0 k u)
                                            .e:C
                                              .h:nat
                                                .d:nat
                                                  .H2:drop h (S (plus (S i0) d)) (CHead c1 (Bind b) t) e
                                                    .ex3_2
                                                      T
                                                      C
                                                      λv:T.λ:C.eq T u (lift h (r k d) v)
                                                      λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                      λ:T.λe0:C.drop h (r k d) c0 e0
                                            assume tT
                                            suppose H1drop (S i0) O (CHead c1 (Bind b) t) (CHead c0 k u)
                                            assume eC
                                            assume hnat
                                            assume dnat
                                            suppose H2drop h (S (plus (S i0) d)) (CHead c1 (Bind b) t) e
                                              by (drop_gen_skip_l . . . . . . H2)
                                              we proved 
                                                 ex3_2
                                                   C
                                                   T
                                                   λe:C.λv:T.eq C e (CHead e (Bind b) v)
                                                   λ:C.λv:T.eq T t (lift h (r (Bind b) (plus (S i0) d)) v)
                                                   λe:C.λ:T.drop h (r (Bind b) (plus (S i0) d)) c1 e
                                              we proceed by induction on the previous result to prove 
                                                 ex3_2
                                                   T
                                                   C
                                                   λv:T.λ:C.eq T u (lift h (r k d) v)
                                                   λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                   λ:T.λe0:C.drop h (r k d) c0 e0
                                                 case ex3_2_intro : x0:C x1:T H3:eq C e (CHead x0 (Bind b) x1) :eq T t (lift h (r (Bind b) (plus (S i0) d)) x1) H5:drop h (r (Bind b) (plus (S i0) d)) c1 x0 
                                                    the thesis becomes 
                                                    ex3_2
                                                      T
                                                      C
                                                      λv:T.λ:C.eq T u (lift h (r k d) v)
                                                      λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                      λ:T.λe0:C.drop h (r k d) c0 e0
                                                       (H6
                                                          (h1
                                                             by (drop_gen_drop . . . . . H1)
                                                             we proved drop (r (Bind b) i0) O c1 (CHead c0 k u)
drop i0 O c1 (CHead c0 k u)
                                                          end of h1
                                                          (h2
                                                             consider H5
                                                             we proved drop h (r (Bind b) (plus (S i0) d)) c1 x0
drop h (S (plus i0 d)) c1 x0
                                                          end of h2
                                                          by (H . . . h1 . . . h2)

                                                             ex3_2
                                                               T
                                                               C
                                                               λv:T.λ:C.eq T u (lift h (r k d) v)
                                                               λv:T.λe0:C.drop i0 O x0 (CHead e0 k v)
                                                               λ:T.λe0:C.drop h (r k d) c0 e0
                                                       end of H6
                                                       we proceed by induction on H6 to prove 
                                                          ex3_2
                                                            T
                                                            C
                                                            λv:T.λ:C.eq T u (lift h (r k d) v)
                                                            λv:T.λe0:C.drop (S i0) O (CHead x0 (Bind b) x1) (CHead e0 k v)
                                                            λ:T.λe0:C.drop h (r k d) c0 e0
                                                          case ex3_2_intro : x2:T x3:C H7:eq T u (lift h (r k d) x2) H8:drop i0 O x0 (CHead x3 k x2) H9:drop h (r k d) c0 x3 
                                                             the thesis becomes 
                                                             ex3_2
                                                               T
                                                               C
                                                               λv:T.λ:C.eq T u (lift h (r k d) v)
                                                               λv:T.λe0:C.drop (S i0) O (CHead x0 (Bind b) x1) (CHead e0 k v)
                                                               λ:T.λe0:C.drop h (r k d) c0 e0
                                                                consider H8
                                                                we proved drop i0 O x0 (CHead x3 k x2)
                                                                that is equivalent to drop (r (Bind b) i0) O x0 (CHead x3 k x2)
                                                                by (drop_drop . . . . previous .)
                                                                we proved drop (S i0) O (CHead x0 (Bind b) x1) (CHead x3 k x2)
                                                                by (ex3_2_intro . . . . . . . H7 previous H9)

                                                                   ex3_2
                                                                     T
                                                                     C
                                                                     λv:T.λ:C.eq T u (lift h (r k d) v)
                                                                     λv:T.λe0:C.drop (S i0) O (CHead x0 (Bind b) x1) (CHead e0 k v)
                                                                     λ:T.λe0:C.drop h (r k d) c0 e0
                                                       we proved 
                                                          ex3_2
                                                            T
                                                            C
                                                            λv:T.λ:C.eq T u (lift h (r k d) v)
                                                            λv:T.λe0:C.drop (S i0) O (CHead x0 (Bind b) x1) (CHead e0 k v)
                                                            λ:T.λe0:C.drop h (r k d) c0 e0
                                                       by (eq_ind_r . . . previous . H3)

                                                          ex3_2
                                                            T
                                                            C
                                                            λv:T.λ:C.eq T u (lift h (r k d) v)
                                                            λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                            λ:T.λe0:C.drop h (r k d) c0 e0
                                              we proved 
                                                 ex3_2
                                                   T
                                                   C
                                                   λv:T.λ:C.eq T u (lift h (r k d) v)
                                                   λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                   λ:T.λe0:C.drop h (r k d) c0 e0

                                              t:T
                                                .H1:drop (S i0) O (CHead c1 (Bind b) t) (CHead c0 k u)
                                                  .e:C
                                                    .h:nat
                                                      .d:nat
                                                        .H2:drop h (S (plus (S i0) d)) (CHead c1 (Bind b) t) e
                                                          .ex3_2
                                                            T
                                                            C
                                                            λv:T.λ:C.eq T u (lift h (r k d) v)
                                                            λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                            λ:T.λe0:C.drop h (r k d) c0 e0
                                     case Flat : f:F 
                                        the thesis becomes 
                                        t:T
                                          .H1:drop (S i0) O (CHead c1 (Flat f) t) (CHead c0 k u)
                                            .e:C
                                              .h:nat
                                                .d:nat
                                                  .H2:drop h (S (plus (S i0) d)) (CHead c1 (Flat f) t) e
                                                    .ex3_2
                                                      T
                                                      C
                                                      λv:T.λ:C.eq T u (lift h (r k d) v)
                                                      λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                      λ:T.λe0:C.drop h (r k d) c0 e0
                                            assume tT
                                            suppose H1drop (S i0) O (CHead c1 (Flat f) t) (CHead c0 k u)
                                            assume eC
                                            assume hnat
                                            assume dnat
                                            suppose H2drop h (S (plus (S i0) d)) (CHead c1 (Flat f) t) e
                                              by (drop_gen_skip_l . . . . . . H2)
                                              we proved 
                                                 ex3_2
                                                   C
                                                   T
                                                   λe:C.λv:T.eq C e (CHead e (Flat f) v)
                                                   λ:C.λv:T.eq T t (lift h (r (Flat f) (plus (S i0) d)) v)
                                                   λe:C.λ:T.drop h (r (Flat f) (plus (S i0) d)) c1 e
                                              we proceed by induction on the previous result to prove 
                                                 ex3_2
                                                   T
                                                   C
                                                   λv:T.λ:C.eq T u (lift h (r k d) v)
                                                   λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                   λ:T.λe0:C.drop h (r k d) c0 e0
                                                 case ex3_2_intro : x0:C x1:T H3:eq C e (CHead x0 (Flat f) x1) :eq T t (lift h (r (Flat f) (plus (S i0) d)) x1) H5:drop h (r (Flat f) (plus (S i0) d)) c1 x0 
                                                    the thesis becomes 
                                                    ex3_2
                                                      T
                                                      C
                                                      λv:T.λ:C.eq T u (lift h (r k d) v)
                                                      λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                      λ:T.λe0:C.drop h (r k d) c0 e0
                                                       (h1
                                                          by (drop_gen_drop . . . . . H1)
                                                          we proved drop (r (Flat f) i0) O c1 (CHead c0 k u)
drop (S i0) O c1 (CHead c0 k u)
                                                       end of h1
                                                       (h2
                                                          consider H5
                                                          we proved drop h (r (Flat f) (plus (S i0) d)) c1 x0
drop h (S (plus (S i0) d)) c1 x0
                                                       end of h2
                                                       by (H0 h1 . . . h2)
                                                       we proved 
                                                          ex3_2
                                                            T
                                                            C
                                                            λv:T.λ:C.eq T u (lift h (r k d) v)
                                                            λv:T.λe0:C.drop (S i0) O x0 (CHead e0 k v)
                                                            λ:T.λe0:C.drop h (r k d) c0 e0
                                                       we proceed by induction on the previous result to prove 
                                                          ex3_2
                                                            T
                                                            C
                                                            λv:T.λ:C.eq T u (lift h (r k d) v)
                                                            λv:T.λe0:C.drop (S i0) O (CHead x0 (Flat f) x1) (CHead e0 k v)
                                                            λ:T.λe0:C.drop h (r k d) c0 e0
                                                          case ex3_2_intro : x2:T x3:C H6:eq T u (lift h (r k d) x2) H7:drop (S i0) O x0 (CHead x3 k x2) H8:drop h (r k d) c0 x3 
                                                             the thesis becomes 
                                                             ex3_2
                                                               T
                                                               C
                                                               λv:T.λ:C.eq T u (lift h (r k d) v)
                                                               λv:T.λe0:C.drop (S i0) O (CHead x0 (Flat f) x1) (CHead e0 k v)
                                                               λ:T.λe0:C.drop h (r k d) c0 e0
                                                                consider H7
                                                                we proved drop (S i0) O x0 (CHead x3 k x2)
                                                                that is equivalent to drop (r (Flat f) i0) O x0 (CHead x3 k x2)
                                                                by (drop_drop . . . . previous .)
                                                                we proved drop (S i0) O (CHead x0 (Flat f) x1) (CHead x3 k x2)
                                                                by (ex3_2_intro . . . . . . . H6 previous H8)

                                                                   ex3_2
                                                                     T
                                                                     C
                                                                     λv:T.λ:C.eq T u (lift h (r k d) v)
                                                                     λv:T.λe0:C.drop (S i0) O (CHead x0 (Flat f) x1) (CHead e0 k v)
                                                                     λ:T.λe0:C.drop h (r k d) c0 e0
                                                       we proved 
                                                          ex3_2
                                                            T
                                                            C
                                                            λv:T.λ:C.eq T u (lift h (r k d) v)
                                                            λv:T.λe0:C.drop (S i0) O (CHead x0 (Flat f) x1) (CHead e0 k v)
                                                            λ:T.λe0:C.drop h (r k d) c0 e0
                                                       by (eq_ind_r . . . previous . H3)

                                                          ex3_2
                                                            T
                                                            C
                                                            λv:T.λ:C.eq T u (lift h (r k d) v)
                                                            λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                            λ:T.λe0:C.drop h (r k d) c0 e0
                                              we proved 
                                                 ex3_2
                                                   T
                                                   C
                                                   λv:T.λ:C.eq T u (lift h (r k d) v)
                                                   λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                   λ:T.λe0:C.drop h (r k d) c0 e0

                                              t:T
                                                .H1:drop (S i0) O (CHead c1 (Flat f) t) (CHead c0 k u)
                                                  .e:C
                                                    .h:nat
                                                      .d:nat
                                                        .H2:drop h (S (plus (S i0) d)) (CHead c1 (Flat f) t) e
                                                          .ex3_2
                                                            T
                                                            C
                                                            λv:T.λ:C.eq T u (lift h (r k d) v)
                                                            λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                            λ:T.λe0:C.drop h (r k d) c0 e0
                                  we proved 
                                     t:T
                                       .drop (S i0) O (CHead c1 k0 t) (CHead c0 k u)
                                         e:C
                                              .h:nat
                                                .d:nat
                                                  .drop h (S (plus (S i0) d)) (CHead c1 k0 t) e
                                                    (ex3_2
                                                         T
                                                         C
                                                         λv:T.λ:C.eq T u (lift h (r k d) v)
                                                         λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                         λ:T.λe0:C.drop h (r k d) c0 e0)

                                  c1:C
                                    .drop (S i0) O c1 (CHead c0 k u)
                                        e:C
                                             .h:nat
                                               .d:nat
                                                 .drop h (S (plus (S i0) d)) c1 e
                                                   (ex3_2
                                                        T
                                                        C
                                                        λv:T.λ:C.eq T u (lift h (r k d) v)
                                                        λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                        λ:T.λe0:C.drop h (r k d) c0 e0)
                                      k0:K
                                           .t:T
                                             .drop (S i0) O (CHead c1 k0 t) (CHead c0 k u)
                                               e:C
                                                    .h:nat
                                                      .d:nat
                                                        .drop h (S (plus (S i0) d)) (CHead c1 k0 t) e
                                                          (ex3_2
                                                               T
                                                               C
                                                               λv:T.λ:C.eq T u (lift h (r k d) v)
                                                               λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                                               λ:T.λe0:C.drop h (r k d) c0 e0)
                      we proved 
                         drop (S i0) O c (CHead c0 k u)
                           e:C
                                .h:nat
                                  .d:nat
                                    .drop h (S (plus (S i0) d)) c e
                                      (ex3_2
                                           T
                                           C
                                           λv:T.λ:C.eq T u (lift h (r k d) v)
                                           λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                           λ:T.λe0:C.drop h (r k d) c0 e0)

                      u:T
                        .c0:C
                          .c:C
                            .drop (S i0) O c (CHead c0 k u)
                              e:C
                                   .h:nat
                                     .d:nat
                                       .drop h (S (plus (S i0) d)) c e
                                         (ex3_2
                                              T
                                              C
                                              λv:T.λ:C.eq T u (lift h (r k d) v)
                                              λv:T.λe0:C.drop (S i0) O e (CHead e0 k v)
                                              λ:T.λe0:C.drop h (r k d) c0 e0)
          we proved 
             u:T
               .c0:C
                 .c:C
                   .drop i O c (CHead c0 k u)
                     e:C
                          .h:nat
                            .d:nat
                              .drop h (S (plus i d)) c e
                                (ex3_2
                                     T
                                     C
                                     λv:T.λ:C.eq T u (lift h (r k d) v)
                                     λv:T.λe0:C.drop i O e (CHead e0 k v)
                                     λ:T.λe0:C.drop h (r k d) c0 e0)
       we proved 
          k:K
            .i:nat
              .u:T
                .c0:C
                  .c:C
                    .drop i O c (CHead c0 k u)
                      e:C
                           .h:nat
                             .d:nat
                               .drop h (S (plus i d)) c e
                                 (ex3_2
                                      T
                                      C
                                      λv:T.λ:C.eq T u (lift h (r k d) v)
                                      λv:T.λe0:C.drop i O e (CHead e0 k v)
                                      λ:T.λe0:C.drop h (r k d) c0 e0)