DEFINITION sty0_gen_bind()
TYPE =
       g:G
         .b:B
           .c:C
             .u:T
               .t1:T
                 .x:T
                   .sty0 g c (THead (Bind b) u t1) x
                     ex2 T λt2:T.sty0 g (CHead c (Bind b) u) t1 t2 λt2:T.eq T x (THead (Bind b) u t2)
BODY =
        assume gG
        assume bB
        assume cC
        assume uT
        assume t1T
        assume xT
        suppose Hsty0 g c (THead (Bind b) u t1) x
           assume yT
           suppose H0sty0 g c y x
             we proceed by induction on H0 to prove 
                eq T y (THead (Bind b) u t1)
                  ex2 T λt2:T.sty0 g (CHead c (Bind b) u) t1 t2 λt2:T.eq T x (THead (Bind b) u t2)
                case sty0_sort : c0:C n:nat 
                   the thesis becomes 
                   H1:eq T (TSort n) (THead (Bind b) u t1)
                     .ex2
                       T
                       λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                       λt2:T.eq T (TSort (next g n)) (THead (Bind b) u t2)
                      suppose H1eq T (TSort n) (THead (Bind b) u t1)
                         (H2
                            we proceed by induction on H1 to prove 
                               <λ:T.Prop>
                                 CASE THead (Bind b) u t1 OF
                                   TSort True
                                 | TLRef False
                                 | THead   False
                               case refl_equal : 
                                  the thesis becomes 
                                  <λ:T.Prop>
                                    CASE TSort n OF
                                      TSort True
                                    | TLRef False
                                    | THead   False
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE TSort n OF
                                            TSort True
                                          | TLRef False
                                          | THead   False

                               <λ:T.Prop>
                                 CASE THead (Bind b) u t1 OF
                                   TSort True
                                 | TLRef False
                                 | THead   False
                         end of H2
                         consider H2
                         we proved 
                            <λ:T.Prop>
                              CASE THead (Bind b) u t1 OF
                                TSort True
                              | TLRef False
                              | THead   False
                         that is equivalent to False
                         we proceed by induction on the previous result to prove 
                            ex2
                              T
                              λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                              λt2:T.eq T (TSort (next g n)) (THead (Bind b) u t2)
                         we proved 
                            ex2
                              T
                              λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                              λt2:T.eq T (TSort (next g n)) (THead (Bind b) u t2)

                         H1:eq T (TSort n) (THead (Bind b) u t1)
                           .ex2
                             T
                             λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                             λt2:T.eq T (TSort (next g n)) (THead (Bind b) u t2)
                case sty0_abbr : c0:C d:C v:T i:nat :getl i c0 (CHead d (Bind Abbr) v) w:T :sty0 g d v w 
                   the thesis becomes 
                   H4:eq T (TLRef i) (THead (Bind b) u t1)
                     .ex2
                       T
                       λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                       λt2:T.eq T (lift (S i) O w) (THead (Bind b) u t2)
                   () by induction hypothesis we know 
                      eq T v (THead (Bind b) u t1)
                        ex2 T λt2:T.sty0 g (CHead d (Bind b) u) t1 t2 λt2:T.eq T w (THead (Bind b) u t2)
                      suppose H4eq T (TLRef i) (THead (Bind b) u t1)
                         (H5
                            we proceed by induction on H4 to prove 
                               <λ:T.Prop>
                                 CASE THead (Bind b) u t1 OF
                                   TSort False
                                 | TLRef True
                                 | THead   False
                               case refl_equal : 
                                  the thesis becomes 
                                  <λ:T.Prop>
                                    CASE TLRef i OF
                                      TSort False
                                    | TLRef True
                                    | THead   False
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE TLRef i OF
                                            TSort False
                                          | TLRef True
                                          | THead   False

                               <λ:T.Prop>
                                 CASE THead (Bind b) u t1 OF
                                   TSort False
                                 | TLRef True
                                 | THead   False
                         end of H5
                         consider H5
                         we proved 
                            <λ:T.Prop>
                              CASE THead (Bind b) u t1 OF
                                TSort False
                              | TLRef True
                              | THead   False
                         that is equivalent to False
                         we proceed by induction on the previous result to prove 
                            ex2
                              T
                              λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                              λt2:T.eq T (lift (S i) O w) (THead (Bind b) u t2)
                         we proved 
                            ex2
                              T
                              λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                              λt2:T.eq T (lift (S i) O w) (THead (Bind b) u t2)

                         H4:eq T (TLRef i) (THead (Bind b) u t1)
                           .ex2
                             T
                             λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                             λt2:T.eq T (lift (S i) O w) (THead (Bind b) u t2)
                case sty0_abst : c0:C d:C v:T i:nat :getl i c0 (CHead d (Bind Abst) v) w:T :sty0 g d v w 
                   the thesis becomes 
                   H4:eq T (TLRef i) (THead (Bind b) u t1)
                     .ex2
                       T
                       λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                       λt2:T.eq T (lift (S i) O v) (THead (Bind b) u t2)
                   () by induction hypothesis we know 
                      eq T v (THead (Bind b) u t1)
                        ex2 T λt2:T.sty0 g (CHead d (Bind b) u) t1 t2 λt2:T.eq T w (THead (Bind b) u t2)
                      suppose H4eq T (TLRef i) (THead (Bind b) u t1)
                         (H5
                            we proceed by induction on H4 to prove 
                               <λ:T.Prop>
                                 CASE THead (Bind b) u t1 OF
                                   TSort False
                                 | TLRef True
                                 | THead   False
                               case refl_equal : 
                                  the thesis becomes 
                                  <λ:T.Prop>
                                    CASE TLRef i OF
                                      TSort False
                                    | TLRef True
                                    | THead   False
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE TLRef i OF
                                            TSort False
                                          | TLRef True
                                          | THead   False

                               <λ:T.Prop>
                                 CASE THead (Bind b) u t1 OF
                                   TSort False
                                 | TLRef True
                                 | THead   False
                         end of H5
                         consider H5
                         we proved 
                            <λ:T.Prop>
                              CASE THead (Bind b) u t1 OF
                                TSort False
                              | TLRef True
                              | THead   False
                         that is equivalent to False
                         we proceed by induction on the previous result to prove 
                            ex2
                              T
                              λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                              λt2:T.eq T (lift (S i) O v) (THead (Bind b) u t2)
                         we proved 
                            ex2
                              T
                              λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                              λt2:T.eq T (lift (S i) O v) (THead (Bind b) u t2)

                         H4:eq T (TLRef i) (THead (Bind b) u t1)
                           .ex2
                             T
                             λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2
                             λt2:T.eq T (lift (S i) O v) (THead (Bind b) u t2)
                case sty0_bind : b0:B c0:C v:T t0:T t2:T H1:sty0 g (CHead c0 (Bind b0) v) t0 t2 
                   the thesis becomes 
                   H3:eq T (THead (Bind b0) v t0) (THead (Bind b) u t1)
                     .ex2
                       T
                       λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                       λt3:T.eq T (THead (Bind b0) v t2) (THead (Bind b) u t3)
                   (H2) by induction hypothesis we know 
                      eq T t0 (THead (Bind b) u t1)
                        (ex2
                             T
                             λt3:T.sty0 g (CHead (CHead c0 (Bind b0) v) (Bind b) u) t1 t3
                             λt3:T.eq T t2 (THead (Bind b) u t3))
                      suppose H3eq T (THead (Bind b0) v t0) (THead (Bind b) u t1)
                         (H4
                            by (f_equal . . . . . H3)
                            we proved 
                               eq
                                 B
                                 <λ:T.B>
                                   CASE THead (Bind b0) v t0 OF
                                     TSort b0
                                   | TLRef b0
                                   | THead k  <λ:K.B> CASE k OF Bind b1b1 | Flat b0
                                 <λ:T.B>
                                   CASE THead (Bind b) u t1 OF
                                     TSort b0
                                   | TLRef b0
                                   | THead k  <λ:K.B> CASE k OF Bind b1b1 | Flat b0

                               eq
                                 B
                                 λe:T
                                     .<λ:T.B>
                                       CASE e OF
                                         TSort b0
                                       | TLRef b0
                                       | THead k  <λ:K.B> CASE k OF Bind b1b1 | Flat b0
                                   THead (Bind b0) v t0
                                 λe:T
                                     .<λ:T.B>
                                       CASE e OF
                                         TSort b0
                                       | TLRef b0
                                       | THead k  <λ:K.B> CASE k OF Bind b1b1 | Flat b0
                                   THead (Bind b) u t1
                         end of H4
                         (h1
                            (H5
                               by (f_equal . . . . . H3)
                               we proved 
                                  eq
                                    T
                                    <λ:T.T> CASE THead (Bind b0) v t0 OF TSort v | TLRef v | THead  t t
                                    <λ:T.T> CASE THead (Bind b) u t1 OF TSort v | TLRef v | THead  t t

                                  eq
                                    T
                                    λe:T.<λ:T.T> CASE e OF TSort v | TLRef v | THead  t t
                                      THead (Bind b0) v t0
                                    λe:T.<λ:T.T> CASE e OF TSort v | TLRef v | THead  t t
                                      THead (Bind b) u t1
                            end of H5
                            (h1
                               (H6
                                  by (f_equal . . . . . H3)
                                  we proved 
                                     eq
                                       T
                                       <λ:T.T> CASE THead (Bind b0) v t0 OF TSort t0 | TLRef t0 | THead   tt
                                       <λ:T.T> CASE THead (Bind b) u t1 OF TSort t0 | TLRef t0 | THead   tt

                                     eq
                                       T
                                       λe:T.<λ:T.T> CASE e OF TSort t0 | TLRef t0 | THead   tt
                                         THead (Bind b0) v t0
                                       λe:T.<λ:T.T> CASE e OF TSort t0 | TLRef t0 | THead   tt
                                         THead (Bind b) u t1
                               end of H6
                                suppose H7eq T v u
                                suppose H8eq B b0 b
                                  (H9
                                     consider H6
                                     we proved 
                                        eq
                                          T
                                          <λ:T.T> CASE THead (Bind b0) v t0 OF TSort t0 | TLRef t0 | THead   tt
                                          <λ:T.T> CASE THead (Bind b) u t1 OF TSort t0 | TLRef t0 | THead   tt
                                     that is equivalent to eq T t0 t1
                                     we proceed by induction on the previous result to prove 
                                        eq T t1 (THead (Bind b) u t1)
                                          (ex2
                                               T
                                               λt3:T.sty0 g (CHead (CHead c0 (Bind b0) v) (Bind b) u) t1 t3
                                               λt3:T.eq T t2 (THead (Bind b) u t3))
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H2

                                        eq T t1 (THead (Bind b) u t1)
                                          (ex2
                                               T
                                               λt3:T.sty0 g (CHead (CHead c0 (Bind b0) v) (Bind b) u) t1 t3
                                               λt3:T.eq T t2 (THead (Bind b) u t3))
                                  end of H9
                                  (H10
                                     consider H6
                                     we proved 
                                        eq
                                          T
                                          <λ:T.T> CASE THead (Bind b0) v t0 OF TSort t0 | TLRef t0 | THead   tt
                                          <λ:T.T> CASE THead (Bind b) u t1 OF TSort t0 | TLRef t0 | THead   tt
                                     that is equivalent to eq T t0 t1
                                     we proceed by induction on the previous result to prove sty0 g (CHead c0 (Bind b0) v) t1 t2
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H1
sty0 g (CHead c0 (Bind b0) v) t1 t2
                                  end of H10
                                  (H11
                                     we proceed by induction on H7 to prove 
                                        eq T t1 (THead (Bind b) u t1)
                                          (ex2
                                               T
                                               λt3:T.sty0 g (CHead (CHead c0 (Bind b0) u) (Bind b) u) t1 t3
                                               λt3:T.eq T t2 (THead (Bind b) u t3))
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H9

                                        eq T t1 (THead (Bind b) u t1)
                                          (ex2
                                               T
                                               λt3:T.sty0 g (CHead (CHead c0 (Bind b0) u) (Bind b) u) t1 t3
                                               λt3:T.eq T t2 (THead (Bind b) u t3))
                                  end of H11
                                  (H12
                                     we proceed by induction on H7 to prove sty0 g (CHead c0 (Bind b0) u) t1 t2
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H10
sty0 g (CHead c0 (Bind b0) u) t1 t2
                                  end of H12
                                  (H14
                                     we proceed by induction on H8 to prove sty0 g (CHead c0 (Bind b) u) t1 t2
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H12
sty0 g (CHead c0 (Bind b) u) t1 t2
                                  end of H14
                                  by (refl_equal . .)
                                  we proved eq T (THead (Bind b) u t2) (THead (Bind b) u t2)
                                  by (ex_intro2 . . . . H14 previous)
                                  we proved 
                                     ex2
                                       T
                                       λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                                       λt3:T.eq T (THead (Bind b) u t2) (THead (Bind b) u t3)
                                  by (eq_ind_r . . . previous . H8)
                                  we proved 
                                     ex2
                                       T
                                       λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                                       λt3:T.eq T (THead (Bind b0) u t2) (THead (Bind b) u t3)
                                  by (eq_ind_r . . . previous . H7)
                                  we proved 
                                     ex2
                                       T
                                       λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                                       λt3:T.eq T (THead (Bind b0) v t2) (THead (Bind b) u t3)

                                  eq T v u
                                    (eq B b0 b
                                         (ex2
                                              T
                                              λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                                              λt3:T.eq T (THead (Bind b0) v t2) (THead (Bind b) u t3)))
                            end of h1
                            (h2
                               consider H5
                               we proved 
                                  eq
                                    T
                                    <λ:T.T> CASE THead (Bind b0) v t0 OF TSort v | TLRef v | THead  t t
                                    <λ:T.T> CASE THead (Bind b) u t1 OF TSort v | TLRef v | THead  t t
eq T v u
                            end of h2
                            by (h1 h2)

                               eq B b0 b
                                 (ex2
                                      T
                                      λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                                      λt3:T.eq T (THead (Bind b0) v t2) (THead (Bind b) u t3))
                         end of h1
                         (h2
                            consider H4
                            we proved 
                               eq
                                 B
                                 <λ:T.B>
                                   CASE THead (Bind b0) v t0 OF
                                     TSort b0
                                   | TLRef b0
                                   | THead k  <λ:K.B> CASE k OF Bind b1b1 | Flat b0
                                 <λ:T.B>
                                   CASE THead (Bind b) u t1 OF
                                     TSort b0
                                   | TLRef b0
                                   | THead k  <λ:K.B> CASE k OF Bind b1b1 | Flat b0
eq B b0 b
                         end of h2
                         by (h1 h2)
                         we proved 
                            ex2
                              T
                              λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                              λt3:T.eq T (THead (Bind b0) v t2) (THead (Bind b) u t3)

                         H3:eq T (THead (Bind b0) v t0) (THead (Bind b) u t1)
                           .ex2
                             T
                             λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                             λt3:T.eq T (THead (Bind b0) v t2) (THead (Bind b) u t3)
                case sty0_appl : c0:C v:T t0:T t2:T :sty0 g c0 t0 t2 
                   the thesis becomes 
                   H3:eq T (THead (Flat Appl) v t0) (THead (Bind b) u t1)
                     .ex2
                       T
                       λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                       λt3:T.eq T (THead (Flat Appl) v t2) (THead (Bind b) u t3)
                   () by induction hypothesis we know 
                      eq T t0 (THead (Bind b) u t1)
                        ex2 T λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3 λt3:T.eq T t2 (THead (Bind b) u t3)
                      suppose H3eq T (THead (Flat Appl) v t0) (THead (Bind b) u t1)
                         (H4
                            we proceed by induction on H3 to prove 
                               <λ:T.Prop>
                                 CASE THead (Bind b) u t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                               case refl_equal : 
                                  the thesis becomes 
                                  <λ:T.Prop>
                                    CASE THead (Flat Appl) v t0 OF
                                      TSort False
                                    | TLRef False
                                    | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE THead (Flat Appl) v t0 OF
                                            TSort False
                                          | TLRef False
                                          | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True

                               <λ:T.Prop>
                                 CASE THead (Bind b) u t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                         end of H4
                         consider H4
                         we proved 
                            <λ:T.Prop>
                              CASE THead (Bind b) u t1 OF
                                TSort False
                              | TLRef False
                              | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                         that is equivalent to False
                         we proceed by induction on the previous result to prove 
                            ex2
                              T
                              λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                              λt3:T.eq T (THead (Flat Appl) v t2) (THead (Bind b) u t3)
                         we proved 
                            ex2
                              T
                              λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                              λt3:T.eq T (THead (Flat Appl) v t2) (THead (Bind b) u t3)

                         H3:eq T (THead (Flat Appl) v t0) (THead (Bind b) u t1)
                           .ex2
                             T
                             λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                             λt3:T.eq T (THead (Flat Appl) v t2) (THead (Bind b) u t3)
                case sty0_cast : c0:C v1:T v2:T :sty0 g c0 v1 v2 t0:T t2:T :sty0 g c0 t0 t2 
                   the thesis becomes 
                   H5:eq T (THead (Flat Cast) v1 t0) (THead (Bind b) u t1)
                     .ex2
                       T
                       λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                       λt3:T.eq T (THead (Flat Cast) v2 t2) (THead (Bind b) u t3)
                   () by induction hypothesis we know 
                      eq T v1 (THead (Bind b) u t1)
                        ex2 T λt2:T.sty0 g (CHead c0 (Bind b) u) t1 t2 λt2:T.eq T v2 (THead (Bind b) u t2)
                   () by induction hypothesis we know 
                      eq T t0 (THead (Bind b) u t1)
                        ex2 T λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3 λt3:T.eq T t2 (THead (Bind b) u t3)
                      suppose H5eq T (THead (Flat Cast) v1 t0) (THead (Bind b) u t1)
                         (H6
                            we proceed by induction on H5 to prove 
                               <λ:T.Prop>
                                 CASE THead (Bind b) u t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                               case refl_equal : 
                                  the thesis becomes 
                                  <λ:T.Prop>
                                    CASE THead (Flat Cast) v1 t0 OF
                                      TSort False
                                    | TLRef False
                                    | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE THead (Flat Cast) v1 t0 OF
                                            TSort False
                                          | TLRef False
                                          | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True

                               <λ:T.Prop>
                                 CASE THead (Bind b) u t1 OF
                                   TSort False
                                 | TLRef False
                                 | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                         end of H6
                         consider H6
                         we proved 
                            <λ:T.Prop>
                              CASE THead (Bind b) u t1 OF
                                TSort False
                              | TLRef False
                              | THead k  <λ:K.Prop> CASE k OF Bind False | Flat True
                         that is equivalent to False
                         we proceed by induction on the previous result to prove 
                            ex2
                              T
                              λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                              λt3:T.eq T (THead (Flat Cast) v2 t2) (THead (Bind b) u t3)
                         we proved 
                            ex2
                              T
                              λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                              λt3:T.eq T (THead (Flat Cast) v2 t2) (THead (Bind b) u t3)

                         H5:eq T (THead (Flat Cast) v1 t0) (THead (Bind b) u t1)
                           .ex2
                             T
                             λt3:T.sty0 g (CHead c0 (Bind b) u) t1 t3
                             λt3:T.eq T (THead (Flat Cast) v2 t2) (THead (Bind b) u t3)
             we proved 
                eq T y (THead (Bind b) u t1)
                  ex2 T λt2:T.sty0 g (CHead c (Bind b) u) t1 t2 λt2:T.eq T x (THead (Bind b) u t2)
          we proved 
             y:T
               .sty0 g c y x
                 (eq T y (THead (Bind b) u t1)
                      ex2 T λt2:T.sty0 g (CHead c (Bind b) u) t1 t2 λt2:T.eq T x (THead (Bind b) u t2))
          by (insert_eq . . . . previous H)
          we proved ex2 T λt2:T.sty0 g (CHead c (Bind b) u) t1 t2 λt2:T.eq T x (THead (Bind b) u t2)
       we proved 
          g:G
            .b:B
              .c:C
                .u:T
                  .t1:T
                    .x:T
                      .sty0 g c (THead (Bind b) u t1) x
                        ex2 T λt2:T.sty0 g (CHead c (Bind b) u) t1 t2 λt2:T.eq T x (THead (Bind b) u t2)