DEFINITION ty3_gen_bind()
TYPE =
       g:G
         .b:B
           .c:C
             .u:T
               .t1:T
                 .x:T
                   .ty3 g c (THead (Bind b) u t1) x
                     (ex3_2
                          T
                          T
                          λt2:T.λ:T.pc3 c (THead (Bind b) u t2) x
                          λ:T.λt:T.ty3 g c u t
                          λt2:T.λ:T.ty3 g (CHead c (Bind b) u) t1 t2)
BODY =
        assume gG
        assume bB
        assume cC
        assume uT
        assume t1T
        assume xT
        suppose Hty3 g c (THead (Bind b) u t1) x
           assume yT
           suppose H0ty3 g c y x
             we proceed by induction on H0 to prove 
                eq T y (THead (Bind b) u t1)
                  (ex3_2
                       T
                       T
                       λt2:T.λ:T.pc3 c (THead (Bind b) u t2) x
                       λ:T.λt3:T.ty3 g c u t3
                       λt2:T.λ:T.ty3 g (CHead c (Bind b) u) t1 t2)
                case ty3_conv : c0:C t2:T t:T :ty3 g c0 t2 t u0:T t0:T H3:ty3 g c0 u0 t0 H5:pc3 c0 t0 t2 
                   the thesis becomes 
                   H6:eq T u0 (THead (Bind b) u t1)
                     .ex3_2
                       T
                       T
                       λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) t2
                       λ:T.λt4:T.ty3 g c0 u t4
                       λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3
                   () by induction hypothesis we know 
                      eq T t2 (THead (Bind b) u t1)
                        (ex3_2
                             T
                             T
                             λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) t
                             λ:T.λt0:T.ty3 g c0 u t0
                             λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3)
                   (H4) by induction hypothesis we know 
                      eq T u0 (THead (Bind b) u t1)
                        (ex3_2
                             T
                             T
                             λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) t0
                             λ:T.λt4:T.ty3 g c0 u t4
                             λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3)
                      suppose H6eq T u0 (THead (Bind b) u t1)
                         (H7
                            by (f_equal . . . . . H6)
                            we proved eq T u0 (THead (Bind b) u t1)
eq T (λe:T.e u0) (λe:T.e (THead (Bind b) u t1))
                         end of H7
                         (H8
                            we proceed by induction on H7 to prove 
                               eq T (THead (Bind b) u t1) (THead (Bind b) u t1)
                                 (ex3_2
                                      T
                                      T
                                      λt4:T.λ:T.pc3 c0 (THead (Bind b) u t4) t0
                                      λ:T.λt5:T.ty3 g c0 u t5
                                      λt4:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t4)
                               case refl_equal : 
                                  the thesis becomes the hypothesis H4

                               eq T (THead (Bind b) u t1) (THead (Bind b) u t1)
                                 (ex3_2
                                      T
                                      T
                                      λt4:T.λ:T.pc3 c0 (THead (Bind b) u t4) t0
                                      λ:T.λt5:T.ty3 g c0 u t5
                                      λt4:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t4)
                         end of H8
                         (H10
                            by (refl_equal . .)
                            we proved eq T (THead (Bind b) u t1) (THead (Bind b) u t1)
                            by (H8 previous)

                               ex3_2
                                 T
                                 T
                                 λt4:T.λ:T.pc3 c0 (THead (Bind b) u t4) t0
                                 λ:T.λt5:T.ty3 g c0 u t5
                                 λt4:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t4
                         end of H10
                         we proceed by induction on H10 to prove 
                            ex3_2
                              T
                              T
                              λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) t2
                              λ:T.λt4:T.ty3 g c0 u t4
                              λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3
                            case ex3_2_intro : x0:T x1:T H11:pc3 c0 (THead (Bind b) u x0) t0 H12:ty3 g c0 u x1 H13:ty3 g (CHead c0 (Bind b) u) t1 x0 
                               the thesis becomes 
                               ex3_2
                                 T
                                 T
                                 λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) t2
                                 λ:T.λt4:T.ty3 g c0 u t4
                                 λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3
                                  by (pc3_t . . . H11 . H5)
                                  we proved pc3 c0 (THead (Bind b) u x0) t2
                                  by (ex3_2_intro . . . . . . . previous H12 H13)

                                     ex3_2
                                       T
                                       T
                                       λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) t2
                                       λ:T.λt4:T.ty3 g c0 u t4
                                       λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3
                         we proved 
                            ex3_2
                              T
                              T
                              λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) t2
                              λ:T.λt4:T.ty3 g c0 u t4
                              λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3

                         H6:eq T u0 (THead (Bind b) u t1)
                           .ex3_2
                             T
                             T
                             λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) t2
                             λ:T.λt4:T.ty3 g c0 u t4
                             λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3
                case ty3_sort : c0:C m:nat 
                   the thesis becomes 
                   H1:eq T (TSort m) (THead (Bind b) u t1)
                     .ex3_2
                       T
                       T
                       λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (TSort (next g m))
                       λ:T.λt:T.ty3 g c0 u t
                       λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                      suppose H1eq T (TSort m) (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 m OF
                                      TSort True
                                    | TLRef False
                                    | THead   False
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE TSort m 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 
                            ex3_2
                              T
                              T
                              λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (TSort (next g m))
                              λ:T.λt:T.ty3 g c0 u t
                              λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                         we proved 
                            ex3_2
                              T
                              T
                              λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (TSort (next g m))
                              λ:T.λt:T.ty3 g c0 u t
                              λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2

                         H1:eq T (TSort m) (THead (Bind b) u t1)
                           .ex3_2
                             T
                             T
                             λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (TSort (next g m))
                             λ:T.λt:T.ty3 g c0 u t
                             λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                case ty3_abbr : n:nat c0:C d:C u0:T :getl n c0 (CHead d (Bind Abbr) u0) t:T :ty3 g d u0 t 
                   the thesis becomes 
                   H4:eq T (TLRef n) (THead (Bind b) u t1)
                     .ex3_2
                       T
                       T
                       λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (lift (S n) O t)
                       λ:T.λt0:T.ty3 g c0 u t0
                       λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                   () by induction hypothesis we know 
                      eq T u0 (THead (Bind b) u t1)
                        (ex3_2
                             T
                             T
                             λt2:T.λ:T.pc3 d (THead (Bind b) u t2) t
                             λ:T.λt0:T.ty3 g d u t0
                             λt2:T.λ:T.ty3 g (CHead d (Bind b) u) t1 t2)
                      suppose H4eq T (TLRef n) (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 n OF
                                      TSort False
                                    | TLRef True
                                    | THead   False
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE TLRef n 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 
                            ex3_2
                              T
                              T
                              λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (lift (S n) O t)
                              λ:T.λt0:T.ty3 g c0 u t0
                              λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                         we proved 
                            ex3_2
                              T
                              T
                              λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (lift (S n) O t)
                              λ:T.λt0:T.ty3 g c0 u t0
                              λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2

                         H4:eq T (TLRef n) (THead (Bind b) u t1)
                           .ex3_2
                             T
                             T
                             λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (lift (S n) O t)
                             λ:T.λt0:T.ty3 g c0 u t0
                             λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                case ty3_abst : n:nat c0:C d:C u0:T :getl n c0 (CHead d (Bind Abst) u0) t:T :ty3 g d u0 t 
                   the thesis becomes 
                   H4:eq T (TLRef n) (THead (Bind b) u t1)
                     .ex3_2
                       T
                       T
                       λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (lift (S n) O u0)
                       λ:T.λt0:T.ty3 g c0 u t0
                       λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                   () by induction hypothesis we know 
                      eq T u0 (THead (Bind b) u t1)
                        (ex3_2
                             T
                             T
                             λt2:T.λ:T.pc3 d (THead (Bind b) u t2) t
                             λ:T.λt0:T.ty3 g d u t0
                             λt2:T.λ:T.ty3 g (CHead d (Bind b) u) t1 t2)
                      suppose H4eq T (TLRef n) (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 n OF
                                      TSort False
                                    | TLRef True
                                    | THead   False
                                     consider I
                                     we proved True

                                        <λ:T.Prop>
                                          CASE TLRef n 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 
                            ex3_2
                              T
                              T
                              λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (lift (S n) O u0)
                              λ:T.λt0:T.ty3 g c0 u t0
                              λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                         we proved 
                            ex3_2
                              T
                              T
                              λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (lift (S n) O u0)
                              λ:T.λt0:T.ty3 g c0 u t0
                              λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2

                         H4:eq T (TLRef n) (THead (Bind b) u t1)
                           .ex3_2
                             T
                             T
                             λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (lift (S n) O u0)
                             λ:T.λt0:T.ty3 g c0 u t0
                             λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                case ty3_bind : c0:C u0:T t:T H1:ty3 g c0 u0 t b0:B t0:T t2:T H3:ty3 g (CHead c0 (Bind b0) u0) t0 t2 
                   the thesis becomes 
                   H5:eq T (THead (Bind b0) u0 t0) (THead (Bind b) u t1)
                     .ex3_2
                       T
                       T
                       λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) (THead (Bind b0) u0 t2)
                       λ:T.λt4:T.ty3 g c0 u t4
                       λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3
                   (H2) by induction hypothesis we know 
                      eq T u0 (THead (Bind b) u t1)
                        (ex3_2
                             T
                             T
                             λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) t
                             λ:T.λt0:T.ty3 g c0 u t0
                             λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2)
                   (H4) by induction hypothesis we know 
                      eq T t0 (THead (Bind b) u t1)
                        (ex3_2
                             T
                             T
                             λt3:T.λ:T.pc3 (CHead c0 (Bind b0) u0) (THead (Bind b) u t3) t2
                             λ:T.λt4:T.ty3 g (CHead c0 (Bind b0) u0) u t4
                             λt3:T.λ:T.ty3 g (CHead (CHead c0 (Bind b0) u0) (Bind b) u) t1 t3)
                      suppose H5eq T (THead (Bind b0) u0 t0) (THead (Bind b) u t1)
                         (H6
                            by (f_equal . . . . . H5)
                            we proved 
                               eq
                                 B
                                 <λ:T.B>
                                   CASE THead (Bind b0) u0 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) u0 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 H6
                         (h1
                            (H7
                               by (f_equal . . . . . H5)
                               we proved 
                                  eq
                                    T
                                    <λ:T.T> CASE THead (Bind b0) u0 t0 OF TSort u0 | TLRef u0 | THead  t3 t3
                                    <λ:T.T> CASE THead (Bind b) u t1 OF TSort u0 | TLRef u0 | THead  t3 t3

                                  eq
                                    T
                                    λe:T.<λ:T.T> CASE e OF TSort u0 | TLRef u0 | THead  t3 t3 (THead (Bind b0) u0 t0)
                                    λe:T.<λ:T.T> CASE e OF TSort u0 | TLRef u0 | THead  t3 t3
                                      THead (Bind b) u t1
                            end of H7
                            (h1
                               (H8
                                  by (f_equal . . . . . H5)
                                  we proved 
                                     eq
                                       T
                                       <λ:T.T> CASE THead (Bind b0) u0 t0 OF TSort t0 | TLRef t0 | THead   t3t3
                                       <λ:T.T> CASE THead (Bind b) u t1 OF TSort t0 | TLRef t0 | THead   t3t3

                                     eq
                                       T
                                       λe:T.<λ:T.T> CASE e OF TSort t0 | TLRef t0 | THead   t3t3 (THead (Bind b0) u0 t0)
                                       λe:T.<λ:T.T> CASE e OF TSort t0 | TLRef t0 | THead   t3t3
                                         THead (Bind b) u t1
                               end of H8
                                suppose H9eq T u0 u
                                suppose H10eq B b0 b
                                  (H11
                                     consider H8
                                     we proved 
                                        eq
                                          T
                                          <λ:T.T> CASE THead (Bind b0) u0 t0 OF TSort t0 | TLRef t0 | THead   t3t3
                                          <λ:T.T> CASE THead (Bind b) u t1 OF TSort t0 | TLRef t0 | THead   t3t3
                                     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)
                                          (ex3_2
                                               T
                                               T
                                               λt4:T.λ:T.pc3 (CHead c0 (Bind b0) u0) (THead (Bind b) u t4) t2
                                               λ:T.λt5:T.ty3 g (CHead c0 (Bind b0) u0) u t5
                                               λt4:T.λ:T.ty3 g (CHead (CHead c0 (Bind b0) u0) (Bind b) u) t1 t4)
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H4

                                        eq T t1 (THead (Bind b) u t1)
                                          (ex3_2
                                               T
                                               T
                                               λt4:T.λ:T.pc3 (CHead c0 (Bind b0) u0) (THead (Bind b) u t4) t2
                                               λ:T.λt5:T.ty3 g (CHead c0 (Bind b0) u0) u t5
                                               λt4:T.λ:T.ty3 g (CHead (CHead c0 (Bind b0) u0) (Bind b) u) t1 t4)
                                  end of H11
                                  (H12
                                     consider H8
                                     we proved 
                                        eq
                                          T
                                          <λ:T.T> CASE THead (Bind b0) u0 t0 OF TSort t0 | TLRef t0 | THead   t3t3
                                          <λ:T.T> CASE THead (Bind b) u t1 OF TSort t0 | TLRef t0 | THead   t3t3
                                     that is equivalent to eq T t0 t1
                                     we proceed by induction on the previous result to prove ty3 g (CHead c0 (Bind b0) u0) t1 t2
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H3
ty3 g (CHead c0 (Bind b0) u0) t1 t2
                                  end of H12
                                  (H13
                                     we proceed by induction on H10 to prove 
                                        eq T t1 (THead (Bind b) u t1)
                                          (ex3_2
                                               T
                                               T
                                               λt3:T.λ:T.pc3 (CHead c0 (Bind b) u0) (THead (Bind b) u t3) t2
                                               λ:T.λt4:T.ty3 g (CHead c0 (Bind b) u0) u t4
                                               λt3:T.λ:T.ty3 g (CHead (CHead c0 (Bind b) u0) (Bind b) u) t1 t3)
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H11

                                        eq T t1 (THead (Bind b) u t1)
                                          (ex3_2
                                               T
                                               T
                                               λt3:T.λ:T.pc3 (CHead c0 (Bind b) u0) (THead (Bind b) u t3) t2
                                               λ:T.λt4:T.ty3 g (CHead c0 (Bind b) u0) u t4
                                               λt3:T.λ:T.ty3 g (CHead (CHead c0 (Bind b) u0) (Bind b) u) t1 t3)
                                  end of H13
                                  (H14
                                     we proceed by induction on H10 to prove ty3 g (CHead c0 (Bind b) u0) t1 t2
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H12
ty3 g (CHead c0 (Bind b) u0) t1 t2
                                  end of H14
                                  (H16
                                     we proceed by induction on H9 to prove ty3 g (CHead c0 (Bind b) u) t1 t2
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H14
ty3 g (CHead c0 (Bind b) u) t1 t2
                                  end of H16
                                  (H18
                                     we proceed by induction on H9 to prove ty3 g c0 u t
                                        case refl_equal : 
                                           the thesis becomes the hypothesis H1
ty3 g c0 u t
                                  end of H18
                                  by (pc3_refl . .)
                                  we proved pc3 c0 (THead (Bind b) u t2) (THead (Bind b) u t2)
                                  by (ex3_2_intro . . . . . . . previous H18 H16)
                                  we proved 
                                     ex3_2
                                       T
                                       T
                                       λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) (THead (Bind b) u t2)
                                       λ:T.λt4:T.ty3 g c0 u t4
                                       λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3
                                  by (eq_ind_r . . . previous . H9)
                                  we proved 
                                     ex3_2
                                       T
                                       T
                                       λt4:T.λ:T.pc3 c0 (THead (Bind b) u t4) (THead (Bind b) u0 t2)
                                       λ:T.λt5:T.ty3 g c0 u t5
                                       λt4:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t4
                                  by (eq_ind_r . . . previous . H10)
                                  we proved 
                                     ex3_2
                                       T
                                       T
                                       λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) (THead (Bind b0) u0 t2)
                                       λ:T.λt4:T.ty3 g c0 u t4
                                       λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3

                                  eq T u0 u
                                    (eq B b0 b
                                         (ex3_2
                                              T
                                              T
                                              λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) (THead (Bind b0) u0 t2)
                                              λ:T.λt4:T.ty3 g c0 u t4
                                              λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3))
                            end of h1
                            (h2
                               consider H7
                               we proved 
                                  eq
                                    T
                                    <λ:T.T> CASE THead (Bind b0) u0 t0 OF TSort u0 | TLRef u0 | THead  t3 t3
                                    <λ:T.T> CASE THead (Bind b) u t1 OF TSort u0 | TLRef u0 | THead  t3 t3
eq T u0 u
                            end of h2
                            by (h1 h2)

                               eq B b0 b
                                 (ex3_2
                                      T
                                      T
                                      λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) (THead (Bind b0) u0 t2)
                                      λ:T.λt4:T.ty3 g c0 u t4
                                      λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3)
                         end of h1
                         (h2
                            consider H6
                            we proved 
                               eq
                                 B
                                 <λ:T.B>
                                   CASE THead (Bind b0) u0 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 
                            ex3_2
                              T
                              T
                              λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) (THead (Bind b0) u0 t2)
                              λ:T.λt4:T.ty3 g c0 u t4
                              λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3

                         H5:eq T (THead (Bind b0) u0 t0) (THead (Bind b) u t1)
                           .ex3_2
                             T
                             T
                             λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) (THead (Bind b0) u0 t2)
                             λ:T.λt4:T.ty3 g c0 u t4
                             λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3
                case ty3_appl : c0:C w:T u0:T :ty3 g c0 w u0 v:T t:T :ty3 g c0 v (THead (Bind Abst) u0 t) 
                   the thesis becomes 
                   H5:eq T (THead (Flat Appl) w v) (THead (Bind b) u t1)
                     .ex3_2
                       T
                       T
                       λt2:T
                         .λ:T
                           .pc3
                             c0
                             THead (Bind b) u t2
                             THead (Flat Appl) w (THead (Bind Abst) u0 t)
                       λ:T.λt0:T.ty3 g c0 u t0
                       λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                   () by induction hypothesis we know 
                      eq T w (THead (Bind b) u t1)
                        (ex3_2
                             T
                             T
                             λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) u0
                             λ:T.λt:T.ty3 g c0 u t
                             λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2)
                   () by induction hypothesis we know 
                      eq T v (THead (Bind b) u t1)
                        (ex3_2
                             T
                             T
                             λt2:T.λ:T.pc3 c0 (THead (Bind b) u t2) (THead (Bind Abst) u0 t)
                             λ:T.λt0:T.ty3 g c0 u t0
                             λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2)
                      suppose H5eq T (THead (Flat Appl) w v) (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 Appl) w v 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) w v 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 
                            ex3_2
                              T
                              T
                              λt2:T
                                .λ:T
                                  .pc3
                                    c0
                                    THead (Bind b) u t2
                                    THead (Flat Appl) w (THead (Bind Abst) u0 t)
                              λ:T.λt0:T.ty3 g c0 u t0
                              λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                         we proved 
                            ex3_2
                              T
                              T
                              λt2:T
                                .λ:T
                                  .pc3
                                    c0
                                    THead (Bind b) u t2
                                    THead (Flat Appl) w (THead (Bind Abst) u0 t)
                              λ:T.λt0:T.ty3 g c0 u t0
                              λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2

                         H5:eq T (THead (Flat Appl) w v) (THead (Bind b) u t1)
                           .ex3_2
                             T
                             T
                             λt2:T
                               .λ:T
                                 .pc3
                                   c0
                                   THead (Bind b) u t2
                                   THead (Flat Appl) w (THead (Bind Abst) u0 t)
                             λ:T.λt0:T.ty3 g c0 u t0
                             λt2:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t2
                case ty3_cast : c0:C t0:T t2:T :ty3 g c0 t0 t2 t3:T :ty3 g c0 t2 t3 
                   the thesis becomes 
                   H5:eq T (THead (Flat Cast) t2 t0) (THead (Bind b) u t1)
                     .ex3_2
                       T
                       T
                       λt4:T.λ:T.pc3 c0 (THead (Bind b) u t4) (THead (Flat Cast) t3 t2)
                       λ:T.λt:T.ty3 g c0 u t
                       λt4:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t4
                   () by induction hypothesis we know 
                      eq T t0 (THead (Bind b) u t1)
                        (ex3_2
                             T
                             T
                             λt3:T.λ:T.pc3 c0 (THead (Bind b) u t3) t2
                             λ:T.λt:T.ty3 g c0 u t
                             λt3:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t3)
                   () by induction hypothesis we know 
                      eq T t2 (THead (Bind b) u t1)
                        (ex3_2
                             T
                             T
                             λt4:T.λ:T.pc3 c0 (THead (Bind b) u t4) t3
                             λ:T.λt:T.ty3 g c0 u t
                             λt4:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t4)
                      suppose H5eq T (THead (Flat Cast) t2 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) t2 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) t2 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 
                            ex3_2
                              T
                              T
                              λt4:T.λ:T.pc3 c0 (THead (Bind b) u t4) (THead (Flat Cast) t3 t2)
                              λ:T.λt:T.ty3 g c0 u t
                              λt4:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t4
                         we proved 
                            ex3_2
                              T
                              T
                              λt4:T.λ:T.pc3 c0 (THead (Bind b) u t4) (THead (Flat Cast) t3 t2)
                              λ:T.λt:T.ty3 g c0 u t
                              λt4:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t4

                         H5:eq T (THead (Flat Cast) t2 t0) (THead (Bind b) u t1)
                           .ex3_2
                             T
                             T
                             λt4:T.λ:T.pc3 c0 (THead (Bind b) u t4) (THead (Flat Cast) t3 t2)
                             λ:T.λt:T.ty3 g c0 u t
                             λt4:T.λ:T.ty3 g (CHead c0 (Bind b) u) t1 t4
             we proved 
                eq T y (THead (Bind b) u t1)
                  (ex3_2
                       T
                       T
                       λt2:T.λ:T.pc3 c (THead (Bind b) u t2) x
                       λ:T.λt3:T.ty3 g c u t3
                       λt2:T.λ:T.ty3 g (CHead c (Bind b) u) t1 t2)
          we proved 
             y:T
               .ty3 g c y x
                 (eq T y (THead (Bind b) u t1)
                      (ex3_2
                           T
                           T
                           λt2:T.λ:T.pc3 c (THead (Bind b) u t2) x
                           λ:T.λt3:T.ty3 g c u t3
                           λt2:T.λ:T.ty3 g (CHead c (Bind b) u) t1 t2))
          by (insert_eq . . . . previous H)
          we proved 
             ex3_2
               T
               T
               λt2:T.λ:T.pc3 c (THead (Bind b) u t2) x
               λ:T.λt0:T.ty3 g c u t0
               λt2:T.λ:T.ty3 g (CHead c (Bind b) u) t1 t2
       we proved 
          g:G
            .b:B
              .c:C
                .u:T
                  .t1:T
                    .x:T
                      .ty3 g c (THead (Bind b) u t1) x
                        (ex3_2
                             T
                             T
                             λt2:T.λ:T.pc3 c (THead (Bind b) u t2) x
                             λ:T.λt0:T.ty3 g c u t0
                             λt2:T.λ:T.ty3 g (CHead c (Bind b) u) t1 t2)