DEFINITION arity_gen_cvoid_subst0()
TYPE =
       g:G
         .c:C
           .t:T
             .a:A
               .arity g c t a
                 d:C
                      .u:T
                        .i:nat
                          .getl i c (CHead d (Bind Void) u)
                            w:T.v:T.(subst0 i w t v)P:Prop.P
BODY =
        assume gG
        assume cC
        assume tT
        assume aA
        suppose Harity g c t a
          we proceed by induction on H to prove 
             d:C
               .u:T
                 .i:nat
                   .getl i c (CHead d (Bind Void) u)
                     w:T.v:T.(subst0 i w t v)P:Prop.P
             case arity_sort : c0:C n:nat 
                the thesis becomes 
                d:C
                  .u:T
                    .i:nat
                      .getl i c0 (CHead d (Bind Void) u)
                        w:T.v:T.H1:(subst0 i w (TSort n) v).P:Prop.P
                    assume dC
                    assume uT
                    assume inat
                    suppose getl i c0 (CHead d (Bind Void) u)
                    assume wT
                    assume vT
                    suppose H1subst0 i w (TSort n) v
                    assume PProp
                      by (subst0_gen_sort . . . . H1 .)
                      we proved P

                      d:C
                        .u:T
                          .i:nat
                            .getl i c0 (CHead d (Bind Void) u)
                              w:T.v:T.H1:(subst0 i w (TSort n) v).P:Prop.P
             case arity_abbr : c0:C d:C u:T i:nat H0:getl i c0 (CHead d (Bind Abbr) u) a0:A :arity g d u a0 
                the thesis becomes 
                d0:C.u0:T.i0:nat.H3:(getl i0 c0 (CHead d0 (Bind Void) u0)).w:T.v:T.H4:(subst0 i0 w (TLRef i) v).P:Prop.P
                () by induction hypothesis we know 
                   d0:C
                     .u0:T
                       .i0:nat
                         .(getl i0 d (CHead d0 (Bind Void) u0))w:T.v:T.(subst0 i0 w u v)P:Prop.P
                    assume d0C
                    assume u0T
                    assume i0nat
                    suppose H3getl i0 c0 (CHead d0 (Bind Void) u0)
                    assume wT
                    assume vT
                    suppose H4subst0 i0 w (TLRef i) v
                    assume PProp
                      by (subst0_gen_lref . . . . H4)
                      we proved land (eq nat i i0) (eq T v (lift (S i) O w))
                      we proceed by induction on the previous result to prove P
                         case conj : H5:eq nat i i0 :eq T v (lift (S i) O w) 
                            the thesis becomes P
                               (H7
                                  by (eq_ind_r . . . H3 . H5)
getl i c0 (CHead d0 (Bind Void) u0)
                               end of H7
                               (H9
                                  by (getl_mono . . . H0 . H7)
                                  we proved eq C (CHead d (Bind Abbr) u) (CHead d0 (Bind Void) u0)
                                  we proceed by induction on the previous result to prove 
                                     <λ:C.Prop>
                                       CASE CHead d0 (Bind Void) 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
                                     case refl_equal : 
                                        the thesis becomes 
                                        <λ:C.Prop>
                                          CASE CHead d (Bind Abbr) 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
                                           consider I
                                           we proved True

                                              <λ:C.Prop>
                                                CASE CHead d (Bind Abbr) 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

                                     <λ:C.Prop>
                                       CASE CHead d0 (Bind Void) 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
                               end of H9
                               consider H9
                               we proved 
                                  <λ:C.Prop>
                                    CASE CHead d0 (Bind Void) 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
                               that is equivalent to False
                               we proceed by induction on the previous result to prove P
P
                      we proved P

                      d0:C.u0:T.i0:nat.H3:(getl i0 c0 (CHead d0 (Bind Void) u0)).w:T.v:T.H4:(subst0 i0 w (TLRef i) v).P:Prop.P
             case arity_abst : c0:C d:C u:T i:nat H0:getl i c0 (CHead d (Bind Abst) u) a0:A :arity g d u (asucc g a0) 
                the thesis becomes 
                d0:C.u0:T.i0:nat.H3:(getl i0 c0 (CHead d0 (Bind Void) u0)).w:T.v:T.H4:(subst0 i0 w (TLRef i) v).P:Prop.P
                () by induction hypothesis we know 
                   d0:C
                     .u0:T
                       .i0:nat
                         .(getl i0 d (CHead d0 (Bind Void) u0))w:T.v:T.(subst0 i0 w u v)P:Prop.P
                    assume d0C
                    assume u0T
                    assume i0nat
                    suppose H3getl i0 c0 (CHead d0 (Bind Void) u0)
                    assume wT
                    assume vT
                    suppose H4subst0 i0 w (TLRef i) v
                    assume PProp
                      by (subst0_gen_lref . . . . H4)
                      we proved land (eq nat i i0) (eq T v (lift (S i) O w))
                      we proceed by induction on the previous result to prove P
                         case conj : H5:eq nat i i0 :eq T v (lift (S i) O w) 
                            the thesis becomes P
                               (H7
                                  by (eq_ind_r . . . H3 . H5)
getl i c0 (CHead d0 (Bind Void) u0)
                               end of H7
                               (H9
                                  by (getl_mono . . . H0 . H7)
                                  we proved eq C (CHead d (Bind Abst) u) (CHead d0 (Bind Void) u0)
                                  we proceed by induction on the previous result to prove 
                                     <λ:C.Prop>
                                       CASE CHead d0 (Bind Void) u0 OF
                                         CSort False
                                       | CHead  k 
                                             <λ:K.Prop>
                                               CASE k OF
                                                 Bind b<λ:B.Prop> CASE b OF AbbrFalse | AbstTrue | VoidFalse
                                               | Flat False
                                     case refl_equal : 
                                        the thesis becomes 
                                        <λ:C.Prop>
                                          CASE CHead d (Bind Abst) u OF
                                            CSort False
                                          | CHead  k 
                                                <λ:K.Prop>
                                                  CASE k OF
                                                    Bind b<λ:B.Prop> CASE b OF AbbrFalse | AbstTrue | VoidFalse
                                                  | Flat False
                                           consider I
                                           we proved True

                                              <λ:C.Prop>
                                                CASE CHead d (Bind Abst) u OF
                                                  CSort False
                                                | CHead  k 
                                                      <λ:K.Prop>
                                                        CASE k OF
                                                          Bind b<λ:B.Prop> CASE b OF AbbrFalse | AbstTrue | VoidFalse
                                                        | Flat False

                                     <λ:C.Prop>
                                       CASE CHead d0 (Bind Void) u0 OF
                                         CSort False
                                       | CHead  k 
                                             <λ:K.Prop>
                                               CASE k OF
                                                 Bind b<λ:B.Prop> CASE b OF AbbrFalse | AbstTrue | VoidFalse
                                               | Flat False
                               end of H9
                               consider H9
                               we proved 
                                  <λ:C.Prop>
                                    CASE CHead d0 (Bind Void) u0 OF
                                      CSort False
                                    | CHead  k 
                                          <λ:K.Prop>
                                            CASE k OF
                                              Bind b<λ:B.Prop> CASE b OF AbbrFalse | AbstTrue | VoidFalse
                                            | Flat False
                               that is equivalent to False
                               we proceed by induction on the previous result to prove P
P
                      we proved P

                      d0:C.u0:T.i0:nat.H3:(getl i0 c0 (CHead d0 (Bind Void) u0)).w:T.v:T.H4:(subst0 i0 w (TLRef i) v).P:Prop.P
             case arity_bind : b:B :not (eq B b Abst) c0:C u:T a1:A :arity g c0 u a1 t0:T a2:A :arity g (CHead c0 (Bind b) u) t0 a2 
                the thesis becomes 
                d:C
                  .u0:T
                    .i:nat
                      .H5:getl i c0 (CHead d (Bind Void) u0)
                        .w:T.v:T.H6:(subst0 i w (THead (Bind b) u t0) v).P:Prop.P
                (H2) by induction hypothesis we know 
                   d:C
                     .u0:T
                       .i:nat
                         .(getl i c0 (CHead d (Bind Void) u0))w:T.v:T.(subst0 i w u v)P:Prop.P
                (H4) by induction hypothesis we know 
                   d:C
                     .u0:T
                       .i:nat
                         .getl i (CHead c0 (Bind b) u) (CHead d (Bind Void) u0)
                           w:T.v:T.(subst0 i w t0 v)P:Prop.P
                    assume dC
                    assume u0T
                    assume inat
                    suppose H5getl i c0 (CHead d (Bind Void) u0)
                    assume wT
                    assume vT
                    suppose H6subst0 i w (THead (Bind b) u t0) v
                    assume PProp
                      by (subst0_gen_head . . . . . . H6)
                      we proved 
                         or3
                           ex2 T λu2:T.eq T v (THead (Bind b) u2 t0) λu2:T.subst0 i w u u2
                           ex2 T λt2:T.eq T v (THead (Bind b) u t2) λt2:T.subst0 (s (Bind b) i) w t0 t2
                           ex3_2
                             T
                             T
                             λu2:T.λt2:T.eq T v (THead (Bind b) u2 t2)
                             λu2:T.λ:T.subst0 i w u u2
                             λ:T.λt2:T.subst0 (s (Bind b) i) w t0 t2
                      we proceed by induction on the previous result to prove P
                         case or3_intro0 : H7:ex2 T λu2:T.eq T v (THead (Bind b) u2 t0) λu2:T.subst0 i w u u2 
                            the thesis becomes P
                               we proceed by induction on H7 to prove P
                                  case ex_intro2 : x:T :eq T v (THead (Bind b) x t0) H9:subst0 i w u x 
                                     the thesis becomes P
                                        by (H2 . . . H5 . . H9 .)
P
P
                         case or3_intro1 : H7:ex2 T λt2:T.eq T v (THead (Bind b) u t2) λt2:T.subst0 (s (Bind b) i) w t0 t2 
                            the thesis becomes P
                               we proceed by induction on H7 to prove P
                                  case ex_intro2 : x:T :eq T v (THead (Bind b) u x) H9:subst0 (s (Bind b) i) w t0 x 
                                     the thesis becomes P
                                        (h1
                                           by (clear_bind . . .)
                                           we proved clear (CHead c0 (Bind b) u) (CHead c0 (Bind b) u)
                                           by (getl_clear_bind . . . . previous . . H5)
getl (S i) (CHead c0 (Bind b) u) (CHead d (Bind Void) u0)
                                        end of h1
                                        (h2
                                           consider H9
                                           we proved subst0 (s (Bind b) i) w t0 x
subst0 (S i) w t0 x
                                        end of h2
                                        by (H4 . . . h1 . . h2 .)
P
P
                         case or3_intro2 : H7:ex3_2 T T λu2:T.λt2:T.eq T v (THead (Bind b) u2 t2) λu2:T.λ:T.subst0 i w u u2 λ:T.λt2:T.subst0 (s (Bind b) i) w t0 t2 
                            the thesis becomes P
                               we proceed by induction on H7 to prove P
                                  case ex3_2_intro : x0:T x1:T :eq T v (THead (Bind b) x0 x1) H9:subst0 i w u x0 :subst0 (s (Bind b) i) w t0 x1 
                                     the thesis becomes P
                                        by (H2 . . . H5 . . H9 .)
P
P
                      we proved P

                      d:C
                        .u0:T
                          .i:nat
                            .H5:getl i c0 (CHead d (Bind Void) u0)
                              .w:T.v:T.H6:(subst0 i w (THead (Bind b) u t0) v).P:Prop.P
             case arity_head : c0:C u:T a1:A :arity g c0 u (asucc g a1) t0:T a2:A :arity g (CHead c0 (Bind Abst) u) t0 a2 
                the thesis becomes 
                d:C
                  .u0:T
                    .i:nat
                      .H4:getl i c0 (CHead d (Bind Void) u0)
                        .w:T.v:T.H5:(subst0 i w (THead (Bind Abst) u t0) v).P:Prop.P
                (H1) by induction hypothesis we know 
                   d:C
                     .u0:T
                       .i:nat
                         .(getl i c0 (CHead d (Bind Void) u0))w:T.v:T.(subst0 i w u v)P:Prop.P
                (H3) by induction hypothesis we know 
                   d:C
                     .u0:T
                       .i:nat
                         .getl i (CHead c0 (Bind Abst) u) (CHead d (Bind Void) u0)
                           w:T.v:T.(subst0 i w t0 v)P:Prop.P
                    assume dC
                    assume u0T
                    assume inat
                    suppose H4getl i c0 (CHead d (Bind Void) u0)
                    assume wT
                    assume vT
                    suppose H5subst0 i w (THead (Bind Abst) u t0) v
                    assume PProp
                      by (subst0_gen_head . . . . . . H5)
                      we proved 
                         or3
                           ex2 T λu2:T.eq T v (THead (Bind Abst) u2 t0) λu2:T.subst0 i w u u2
                           ex2 T λt2:T.eq T v (THead (Bind Abst) u t2) λt2:T.subst0 (s (Bind Abst) i) w t0 t2
                           ex3_2
                             T
                             T
                             λu2:T.λt2:T.eq T v (THead (Bind Abst) u2 t2)
                             λu2:T.λ:T.subst0 i w u u2
                             λ:T.λt2:T.subst0 (s (Bind Abst) i) w t0 t2
                      we proceed by induction on the previous result to prove P
                         case or3_intro0 : H6:ex2 T λu2:T.eq T v (THead (Bind Abst) u2 t0) λu2:T.subst0 i w u u2 
                            the thesis becomes P
                               we proceed by induction on H6 to prove P
                                  case ex_intro2 : x:T :eq T v (THead (Bind Abst) x t0) H8:subst0 i w u x 
                                     the thesis becomes P
                                        by (H1 . . . H4 . . H8 .)
P
P
                         case or3_intro1 : H6:ex2 T λt2:T.eq T v (THead (Bind Abst) u t2) λt2:T.subst0 (s (Bind Abst) i) w t0 t2 
                            the thesis becomes P
                               we proceed by induction on H6 to prove P
                                  case ex_intro2 : x:T :eq T v (THead (Bind Abst) u x) H8:subst0 (s (Bind Abst) i) w t0 x 
                                     the thesis becomes P
                                        (h1
                                           by (clear_bind . . .)
                                           we proved clear (CHead c0 (Bind Abst) u) (CHead c0 (Bind Abst) u)
                                           by (getl_clear_bind . . . . previous . . H4)
getl (S i) (CHead c0 (Bind Abst) u) (CHead d (Bind Void) u0)
                                        end of h1
                                        (h2
                                           consider H8
                                           we proved subst0 (s (Bind Abst) i) w t0 x
subst0 (S i) w t0 x
                                        end of h2
                                        by (H3 . . . h1 . . h2 .)
P
P
                         case or3_intro2 : H6:ex3_2 T T λu2:T.λt2:T.eq T v (THead (Bind Abst) u2 t2) λu2:T.λ:T.subst0 i w u u2 λ:T.λt2:T.subst0 (s (Bind Abst) i) w t0 t2 
                            the thesis becomes P
                               we proceed by induction on H6 to prove P
                                  case ex3_2_intro : x0:T x1:T :eq T v (THead (Bind Abst) x0 x1) H8:subst0 i w u x0 :subst0 (s (Bind Abst) i) w t0 x1 
                                     the thesis becomes P
                                        by (H1 . . . H4 . . H8 .)
P
P
                      we proved P

                      d:C
                        .u0:T
                          .i:nat
                            .H4:getl i c0 (CHead d (Bind Void) u0)
                              .w:T.v:T.H5:(subst0 i w (THead (Bind Abst) u t0) v).P:Prop.P
             case arity_appl : c0:C u:T a1:A :arity g c0 u a1 t0:T a2:A :arity g c0 t0 (AHead a1 a2) 
                the thesis becomes 
                d:C
                  .u0:T
                    .i:nat
                      .H4:getl i c0 (CHead d (Bind Void) u0)
                        .w:T.v:T.H5:(subst0 i w (THead (Flat Appl) u t0) v).P:Prop.P
                (H1) by induction hypothesis we know 
                   d:C
                     .u0:T
                       .i:nat
                         .(getl i c0 (CHead d (Bind Void) u0))w:T.v:T.(subst0 i w u v)P:Prop.P
                (H3) by induction hypothesis we know 
                   d:C
                     .u0:T
                       .i:nat
                         .(getl i c0 (CHead d (Bind Void) u0))w:T.v:T.(subst0 i w t0 v)P:Prop.P
                    assume dC
                    assume u0T
                    assume inat
                    suppose H4getl i c0 (CHead d (Bind Void) u0)
                    assume wT
                    assume vT
                    suppose H5subst0 i w (THead (Flat Appl) u t0) v
                    assume PProp
                      by (subst0_gen_head . . . . . . H5)
                      we proved 
                         or3
                           ex2 T λu2:T.eq T v (THead (Flat Appl) u2 t0) λu2:T.subst0 i w u u2
                           ex2 T λt2:T.eq T v (THead (Flat Appl) u t2) λt2:T.subst0 (s (Flat Appl) i) w t0 t2
                           ex3_2
                             T
                             T
                             λu2:T.λt2:T.eq T v (THead (Flat Appl) u2 t2)
                             λu2:T.λ:T.subst0 i w u u2
                             λ:T.λt2:T.subst0 (s (Flat Appl) i) w t0 t2
                      we proceed by induction on the previous result to prove P
                         case or3_intro0 : H6:ex2 T λu2:T.eq T v (THead (Flat Appl) u2 t0) λu2:T.subst0 i w u u2 
                            the thesis becomes P
                               we proceed by induction on H6 to prove P
                                  case ex_intro2 : x:T :eq T v (THead (Flat Appl) x t0) H8:subst0 i w u x 
                                     the thesis becomes P
                                        by (H1 . . . H4 . . H8 .)
P
P
                         case or3_intro1 : H6:ex2 T λt2:T.eq T v (THead (Flat Appl) u t2) λt2:T.subst0 (s (Flat Appl) i) w t0 t2 
                            the thesis becomes P
                               we proceed by induction on H6 to prove P
                                  case ex_intro2 : x:T :eq T v (THead (Flat Appl) u x) H8:subst0 (s (Flat Appl) i) w t0 x 
                                     the thesis becomes P
                                        consider H8
                                        we proved subst0 (s (Flat Appl) i) w t0 x
                                        that is equivalent to subst0 i w t0 x
                                        by (H3 . . . H4 . . previous .)
P
P
                         case or3_intro2 : H6:ex3_2 T T λu2:T.λt2:T.eq T v (THead (Flat Appl) u2 t2) λu2:T.λ:T.subst0 i w u u2 λ:T.λt2:T.subst0 (s (Flat Appl) i) w t0 t2 
                            the thesis becomes P
                               we proceed by induction on H6 to prove P
                                  case ex3_2_intro : x0:T x1:T :eq T v (THead (Flat Appl) x0 x1) H8:subst0 i w u x0 :subst0 (s (Flat Appl) i) w t0 x1 
                                     the thesis becomes P
                                        by (H1 . . . H4 . . H8 .)
P
P
                      we proved P

                      d:C
                        .u0:T
                          .i:nat
                            .H4:getl i c0 (CHead d (Bind Void) u0)
                              .w:T.v:T.H5:(subst0 i w (THead (Flat Appl) u t0) v).P:Prop.P
             case arity_cast : c0:C u:T a0:A :arity g c0 u (asucc g a0) t0:T :arity g c0 t0 a0 
                the thesis becomes 
                d:C
                  .u0:T
                    .i:nat
                      .H4:getl i c0 (CHead d (Bind Void) u0)
                        .w:T.v:T.H5:(subst0 i w (THead (Flat Cast) u t0) v).P:Prop.P
                (H1) by induction hypothesis we know 
                   d:C
                     .u0:T
                       .i:nat
                         .(getl i c0 (CHead d (Bind Void) u0))w:T.v:T.(subst0 i w u v)P:Prop.P
                (H3) by induction hypothesis we know 
                   d:C
                     .u0:T
                       .i:nat
                         .(getl i c0 (CHead d (Bind Void) u0))w:T.v:T.(subst0 i w t0 v)P:Prop.P
                    assume dC
                    assume u0T
                    assume inat
                    suppose H4getl i c0 (CHead d (Bind Void) u0)
                    assume wT
                    assume vT
                    suppose H5subst0 i w (THead (Flat Cast) u t0) v
                    assume PProp
                      by (subst0_gen_head . . . . . . H5)
                      we proved 
                         or3
                           ex2 T λu2:T.eq T v (THead (Flat Cast) u2 t0) λu2:T.subst0 i w u u2
                           ex2 T λt2:T.eq T v (THead (Flat Cast) u t2) λt2:T.subst0 (s (Flat Cast) i) w t0 t2
                           ex3_2
                             T
                             T
                             λu2:T.λt2:T.eq T v (THead (Flat Cast) u2 t2)
                             λu2:T.λ:T.subst0 i w u u2
                             λ:T.λt2:T.subst0 (s (Flat Cast) i) w t0 t2
                      we proceed by induction on the previous result to prove P
                         case or3_intro0 : H6:ex2 T λu2:T.eq T v (THead (Flat Cast) u2 t0) λu2:T.subst0 i w u u2 
                            the thesis becomes P
                               we proceed by induction on H6 to prove P
                                  case ex_intro2 : x:T :eq T v (THead (Flat Cast) x t0) H8:subst0 i w u x 
                                     the thesis becomes P
                                        by (H1 . . . H4 . . H8 .)
P
P
                         case or3_intro1 : H6:ex2 T λt2:T.eq T v (THead (Flat Cast) u t2) λt2:T.subst0 (s (Flat Cast) i) w t0 t2 
                            the thesis becomes P
                               we proceed by induction on H6 to prove P
                                  case ex_intro2 : x:T :eq T v (THead (Flat Cast) u x) H8:subst0 (s (Flat Cast) i) w t0 x 
                                     the thesis becomes P
                                        consider H8
                                        we proved subst0 (s (Flat Cast) i) w t0 x
                                        that is equivalent to subst0 i w t0 x
                                        by (H3 . . . H4 . . previous .)
P
P
                         case or3_intro2 : H6:ex3_2 T T λu2:T.λt2:T.eq T v (THead (Flat Cast) u2 t2) λu2:T.λ:T.subst0 i w u u2 λ:T.λt2:T.subst0 (s (Flat Cast) i) w t0 t2 
                            the thesis becomes P
                               we proceed by induction on H6 to prove P
                                  case ex3_2_intro : x0:T x1:T :eq T v (THead (Flat Cast) x0 x1) H8:subst0 i w u x0 :subst0 (s (Flat Cast) i) w t0 x1 
                                     the thesis becomes P
                                        by (H1 . . . H4 . . H8 .)
P
P
                      we proved P

                      d:C
                        .u0:T
                          .i:nat
                            .H4:getl i c0 (CHead d (Bind Void) u0)
                              .w:T.v:T.H5:(subst0 i w (THead (Flat Cast) u t0) v).P:Prop.P
             case arity_repl : c0:C t0:T a1:A :arity g c0 t0 a1 a2:A :leq g a1 a2 
                the thesis becomes d:C.u:T.i:nat.H3:(getl i c0 (CHead d (Bind Void) u)).w:T.v:T.H4:(subst0 i w t0 v).P:Prop.P
                (H1) by induction hypothesis we know 
                   d:C
                     .u:T
                       .i:nat
                         .(getl i c0 (CHead d (Bind Void) u))w:T.v:T.(subst0 i w t0 v)P:Prop.P
                    assume dC
                    assume uT
                    assume inat
                    suppose H3getl i c0 (CHead d (Bind Void) u)
                    assume wT
                    assume vT
                    suppose H4subst0 i w t0 v
                    assume PProp
                      by (H1 . . . H3 . . H4 .)
                      we proved P
d:C.u:T.i:nat.H3:(getl i c0 (CHead d (Bind Void) u)).w:T.v:T.H4:(subst0 i w t0 v).P:Prop.P
          we proved 
             d:C
               .u:T
                 .i:nat
                   .getl i c (CHead d (Bind Void) u)
                     w:T.v:T.(subst0 i w t v)P:Prop.P
       we proved 
          g:G
            .c:C
              .t:T
                .a:A
                  .arity g c t a
                    d:C
                         .u:T
                           .i:nat
                             .getl i c (CHead d (Bind Void) u)
                               w:T.v:T.(subst0 i w t v)P:Prop.P