DEFINITION csuba_gen_void_rev()
TYPE =
       g:G
         .d1:C
           .c:C
             .u:T
               .csuba g c (CHead d1 (Bind Void) u)
                 ex2 C λd2:C.eq C c (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
BODY =
        assume gG
        assume d1C
        assume cC
        assume uT
        suppose Hcsuba g c (CHead d1 (Bind Void) u)
           assume yC
           suppose H0csuba g c y
             we proceed by induction on H0 to prove 
                eq C y (CHead d1 (Bind Void) u)
                  ex2 C λd2:C.eq C c (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
                case csuba_sort : n:nat 
                   the thesis becomes 
                   H1:eq C (CSort n) (CHead d1 (Bind Void) u)
                     .ex2 C λd2:C.eq C (CSort n) (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
                      suppose H1eq C (CSort n) (CHead d1 (Bind Void) u)
                         (H2
                            we proceed by induction on H1 to prove 
                               <λ:C.Prop>
                                 CASE CHead d1 (Bind Void) u OF
                                   CSort True
                                 | CHead   False
                               case refl_equal : 
                                  the thesis becomes <λ:C.Prop> CASE CSort n OF CSort True | CHead   False
                                     consider I
                                     we proved True
<λ:C.Prop> CASE CSort n OF CSort True | CHead   False

                               <λ:C.Prop>
                                 CASE CHead d1 (Bind Void) u OF
                                   CSort True
                                 | CHead   False
                         end of H2
                         consider H2
                         we proved 
                            <λ:C.Prop>
                              CASE CHead d1 (Bind Void) u OF
                                CSort True
                              | CHead   False
                         that is equivalent to False
                         we proceed by induction on the previous result to prove ex2 C λd2:C.eq C (CSort n) (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
                         we proved ex2 C λd2:C.eq C (CSort n) (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1

                         H1:eq C (CSort n) (CHead d1 (Bind Void) u)
                           .ex2 C λd2:C.eq C (CSort n) (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
                case csuba_head : c1:C c2:C H1:csuba g c1 c2 k:K u0:T 
                   the thesis becomes 
                   H3:eq C (CHead c2 k u0) (CHead d1 (Bind Void) u)
                     .ex2 C λd2:C.eq C (CHead c1 k u0) (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
                   (H2) by induction hypothesis we know 
                      eq C c2 (CHead d1 (Bind Void) u)
                        ex2 C λd2:C.eq C c1 (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
                      suppose H3eq C (CHead c2 k u0) (CHead d1 (Bind Void) u)
                         (H4
                            by (f_equal . . . . . H3)
                            we proved 
                               eq
                                 C
                                 <λ:C.C> CASE CHead c2 k u0 OF CSort c2 | CHead c0  c0
                                 <λ:C.C> CASE CHead d1 (Bind Void) u OF CSort c2 | CHead c0  c0

                               eq
                                 C
                                 λe:C.<λ:C.C> CASE e OF CSort c2 | CHead c0  c0 (CHead c2 k u0)
                                 λe:C.<λ:C.C> CASE e OF CSort c2 | CHead c0  c0 (CHead d1 (Bind Void) u)
                         end of H4
                         (h1
                            (H5
                               by (f_equal . . . . . H3)
                               we proved 
                                  eq
                                    K
                                    <λ:C.K> CASE CHead c2 k u0 OF CSort k | CHead  k0 k0
                                    <λ:C.K> CASE CHead d1 (Bind Void) u OF CSort k | CHead  k0 k0

                                  eq
                                    K
                                    λe:C.<λ:C.K> CASE e OF CSort k | CHead  k0 k0 (CHead c2 k u0)
                                    λe:C.<λ:C.K> CASE e OF CSort k | CHead  k0 k0 (CHead d1 (Bind Void) u)
                            end of H5
                            (h1
                               (H6
                                  by (f_equal . . . . . H3)
                                  we proved 
                                     eq
                                       T
                                       <λ:C.T> CASE CHead c2 k u0 OF CSort u0 | CHead   tt
                                       <λ:C.T> CASE CHead d1 (Bind Void) u OF CSort u0 | CHead   tt

                                     eq
                                       T
                                       λe:C.<λ:C.T> CASE e OF CSort u0 | CHead   tt (CHead c2 k u0)
                                       λe:C.<λ:C.T> CASE e OF CSort u0 | CHead   tt (CHead d1 (Bind Void) u)
                               end of H6
                                suppose H7eq K k (Bind Void)
                                suppose H8eq C c2 d1
                                  (h1
                                     (H10
                                        we proceed by induction on H8 to prove csuba g c1 d1
                                           case refl_equal : 
                                              the thesis becomes the hypothesis H1
csuba g c1 d1
                                     end of H10
                                     by (refl_equal . .)
                                     we proved eq C (CHead c1 (Bind Void) u) (CHead c1 (Bind Void) u)
                                     by (ex_intro2 . . . . previous H10)
                                     we proved 
                                        ex2
                                          C
                                          λd2:C.eq C (CHead c1 (Bind Void) u) (CHead d2 (Bind Void) u)
                                          λd2:C.csuba g d2 d1
                                     by (eq_ind_r . . . previous . H7)
ex2 C λd2:C.eq C (CHead c1 k u) (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
                                  end of h1
                                  (h2
                                     consider H6
                                     we proved 
                                        eq
                                          T
                                          <λ:C.T> CASE CHead c2 k u0 OF CSort u0 | CHead   tt
                                          <λ:C.T> CASE CHead d1 (Bind Void) u OF CSort u0 | CHead   tt
eq T u0 u
                                  end of h2
                                  by (eq_ind_r . . . h1 . h2)
                                  we proved ex2 C λd2:C.eq C (CHead c1 k u0) (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1

                                  eq K k (Bind Void)
                                    (eq C c2 d1
                                         ex2 C λd2:C.eq C (CHead c1 k u0) (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1)
                            end of h1
                            (h2
                               consider H5
                               we proved 
                                  eq
                                    K
                                    <λ:C.K> CASE CHead c2 k u0 OF CSort k | CHead  k0 k0
                                    <λ:C.K> CASE CHead d1 (Bind Void) u OF CSort k | CHead  k0 k0
eq K k (Bind Void)
                            end of h2
                            by (h1 h2)

                               eq C c2 d1
                                 ex2 C λd2:C.eq C (CHead c1 k u0) (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
                         end of h1
                         (h2
                            consider H4
                            we proved 
                               eq
                                 C
                                 <λ:C.C> CASE CHead c2 k u0 OF CSort c2 | CHead c0  c0
                                 <λ:C.C> CASE CHead d1 (Bind Void) u OF CSort c2 | CHead c0  c0
eq C c2 d1
                         end of h2
                         by (h1 h2)
                         we proved ex2 C λd2:C.eq C (CHead c1 k u0) (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1

                         H3:eq C (CHead c2 k u0) (CHead d1 (Bind Void) u)
                           .ex2 C λd2:C.eq C (CHead c1 k u0) (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
                case csuba_void : c1:C c2:C H1:csuba g c1 c2 b:B H3:not (eq B b Void) u1:T u2:T 
                   the thesis becomes 
                   H4:eq C (CHead c2 (Bind b) u2) (CHead d1 (Bind Void) u)
                     .ex2
                       C
                       λd2:C.eq C (CHead c1 (Bind Void) u1) (CHead d2 (Bind Void) u)
                       λd2:C.csuba g d2 d1
                   (H2) by induction hypothesis we know 
                      eq C c2 (CHead d1 (Bind Void) u)
                        ex2 C λd2:C.eq C c1 (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
                      suppose H4eq C (CHead c2 (Bind b) u2) (CHead d1 (Bind Void) u)
                         (H5
                            by (f_equal . . . . . H4)
                            we proved 
                               eq
                                 C
                                 <λ:C.C> CASE CHead c2 (Bind b) u2 OF CSort c2 | CHead c0  c0
                                 <λ:C.C> CASE CHead d1 (Bind Void) u OF CSort c2 | CHead c0  c0

                               eq
                                 C
                                 λe:C.<λ:C.C> CASE e OF CSort c2 | CHead c0  c0 (CHead c2 (Bind b) u2)
                                 λe:C.<λ:C.C> CASE e OF CSort c2 | CHead c0  c0 (CHead d1 (Bind Void) u)
                         end of H5
                         (h1
                            (H6
                               by (f_equal . . . . . H4)
                               we proved 
                                  eq
                                    B
                                    <λ:C.B>
                                      CASE CHead c2 (Bind b) u2 OF
                                        CSort b
                                      | CHead  k <λ:K.B> CASE k OF Bind b0b0 | Flat b
                                    <λ:C.B>
                                      CASE CHead d1 (Bind Void) u OF
                                        CSort b
                                      | CHead  k <λ:K.B> CASE k OF Bind b0b0 | Flat b

                                  eq
                                    B
                                    λe:C.<λ:C.B> CASE e OF CSort b | CHead  k <λ:K.B> CASE k OF Bind b0b0 | Flat b
                                      CHead c2 (Bind b) u2
                                    λe:C.<λ:C.B> CASE e OF CSort b | CHead  k <λ:K.B> CASE k OF Bind b0b0 | Flat b
                                      CHead d1 (Bind Void) u
                            end of H6
                            (H8
                               consider H6
                               we proved 
                                  eq
                                    B
                                    <λ:C.B>
                                      CASE CHead c2 (Bind b) u2 OF
                                        CSort b
                                      | CHead  k <λ:K.B> CASE k OF Bind b0b0 | Flat b
                                    <λ:C.B>
                                      CASE CHead d1 (Bind Void) u OF
                                        CSort b
                                      | CHead  k <λ:K.B> CASE k OF Bind b0b0 | Flat b
eq B b Void
                            end of H8
                            suppose H9eq C c2 d1
                               (H10
                                  we proceed by induction on H8 to prove not (eq B Void Void)
                                     case refl_equal : 
                                        the thesis becomes the hypothesis H3
not (eq B Void Void)
                               end of H10
                               (H13
                                  by (refl_equal . .)
                                  we proved eq B Void Void
                                  by (H10 previous)
                                  we proved False
                                  by cases on the previous result we prove 
                                     ex2
                                       C
                                       λd2:C.eq C (CHead c1 (Bind Void) u1) (CHead d2 (Bind Void) u)
                                       λd2:C.csuba g d2 d1

                                     ex2
                                       C
                                       λd2:C.eq C (CHead c1 (Bind Void) u1) (CHead d2 (Bind Void) u)
                                       λd2:C.csuba g d2 d1
                               end of H13
                               consider H13
                               we proved 
                                  ex2
                                    C
                                    λd2:C.eq C (CHead c1 (Bind Void) u1) (CHead d2 (Bind Void) u)
                                    λd2:C.csuba g d2 d1

                               eq C c2 d1
                                 (ex2
                                      C
                                      λd2:C.eq C (CHead c1 (Bind Void) u1) (CHead d2 (Bind Void) u)
                                      λd2:C.csuba g d2 d1)
                         end of h1
                         (h2
                            consider H5
                            we proved 
                               eq
                                 C
                                 <λ:C.C> CASE CHead c2 (Bind b) u2 OF CSort c2 | CHead c0  c0
                                 <λ:C.C> CASE CHead d1 (Bind Void) u OF CSort c2 | CHead c0  c0
eq C c2 d1
                         end of h2
                         by (h1 h2)
                         we proved 
                            ex2
                              C
                              λd2:C.eq C (CHead c1 (Bind Void) u1) (CHead d2 (Bind Void) u)
                              λd2:C.csuba g d2 d1

                         H4:eq C (CHead c2 (Bind b) u2) (CHead d1 (Bind Void) u)
                           .ex2
                             C
                             λd2:C.eq C (CHead c1 (Bind Void) u1) (CHead d2 (Bind Void) u)
                             λd2:C.csuba g d2 d1
                case csuba_abst : c1:C c2:C :csuba g c1 c2 t:T a:A :arity g c1 t (asucc g a) u0:T :arity g c2 u0 a 
                   the thesis becomes 
                   H5:eq C (CHead c2 (Bind Abbr) u0) (CHead d1 (Bind Void) u)
                     .ex2
                       C
                       λd2:C.eq C (CHead c1 (Bind Abst) t) (CHead d2 (Bind Void) u)
                       λd2:C.csuba g d2 d1
                   () by induction hypothesis we know 
                      eq C c2 (CHead d1 (Bind Void) u)
                        ex2 C λd2:C.eq C c1 (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
                      suppose H5eq C (CHead c2 (Bind Abbr) u0) (CHead d1 (Bind Void) u)
                         (H6
                            we proceed by induction on H5 to prove 
                               <λ:C.Prop>
                                 CASE CHead d1 (Bind Void) u OF
                                   CSort False
                                 | CHead  k 
                                       <λ:K.Prop>
                                         CASE k OF
                                           Bind b<λ:B.Prop> CASE b OF AbbrTrue | AbstFalse | VoidFalse
                                         | Flat False
                               case refl_equal : 
                                  the thesis becomes 
                                  <λ:C.Prop>
                                    CASE CHead c2 (Bind Abbr) u0 OF
                                      CSort False
                                    | CHead  k 
                                          <λ:K.Prop>
                                            CASE k OF
                                              Bind b<λ:B.Prop> CASE b OF AbbrTrue | AbstFalse | VoidFalse
                                            | Flat False
                                     consider I
                                     we proved True

                                        <λ:C.Prop>
                                          CASE CHead c2 (Bind Abbr) u0 OF
                                            CSort False
                                          | CHead  k 
                                                <λ:K.Prop>
                                                  CASE k OF
                                                    Bind b<λ:B.Prop> CASE b OF AbbrTrue | AbstFalse | VoidFalse
                                                  | Flat False

                               <λ:C.Prop>
                                 CASE CHead d1 (Bind Void) u OF
                                   CSort False
                                 | CHead  k 
                                       <λ:K.Prop>
                                         CASE k OF
                                           Bind b<λ:B.Prop> CASE b OF AbbrTrue | AbstFalse | VoidFalse
                                         | Flat False
                         end of H6
                         consider H6
                         we proved 
                            <λ:C.Prop>
                              CASE CHead d1 (Bind Void) u OF
                                CSort False
                              | CHead  k 
                                    <λ:K.Prop>
                                      CASE k OF
                                        Bind b<λ:B.Prop> CASE b OF AbbrTrue | AbstFalse | VoidFalse
                                      | Flat False
                         that is equivalent to False
                         we proceed by induction on the previous result to prove 
                            ex2
                              C
                              λd2:C.eq C (CHead c1 (Bind Abst) t) (CHead d2 (Bind Void) u)
                              λd2:C.csuba g d2 d1
                         we proved 
                            ex2
                              C
                              λd2:C.eq C (CHead c1 (Bind Abst) t) (CHead d2 (Bind Void) u)
                              λd2:C.csuba g d2 d1

                         H5:eq C (CHead c2 (Bind Abbr) u0) (CHead d1 (Bind Void) u)
                           .ex2
                             C
                             λd2:C.eq C (CHead c1 (Bind Abst) t) (CHead d2 (Bind Void) u)
                             λd2:C.csuba g d2 d1
             we proved 
                eq C y (CHead d1 (Bind Void) u)
                  ex2 C λd2:C.eq C c (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
          we proved 
             y:C
               .csuba g c y
                 (eq C y (CHead d1 (Bind Void) u)
                      ex2 C λd2:C.eq C c (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1)
          by (insert_eq . . . . previous H)
          we proved ex2 C λd2:C.eq C c (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1
       we proved 
          g:G
            .d1:C
              .c:C
                .u:T
                  .csuba g c (CHead d1 (Bind Void) u)
                    ex2 C λd2:C.eq C c (CHead d2 (Bind Void) u) λd2:C.csuba g d2 d1