--- /dev/null
+(*#* #stop file *)
+
+Require pc3_props.
+Require csub0_defs.
+
+ Section csub0_pc3. (*****************************************************)
+
+ Theorem csub0_pr2: (g:?; c1:?; t1,t2:?) (pr2 c1 t1 t2) ->
+ (c2:?) (csub0 g c1 c2) -> (pr2 c2 t1 t2).
+ Intros until 1; XElim H; Intros.
+(* case 1: pr2_free *)
+ XAuto.
+(* case 2: pr2_delta *)
+ CSub0Drop; XEAuto.
+ Qed.
+
+ Hints Resolve csub0_pr2.
+
+ Opaque pc3.
+
+ Theorem csub0_pc3: (g:?; c1:?; t1,t2:?) (pc3 c1 t1 t2) ->
+ (c2:?) (csub0 g c1 c2) -> (pc3 c2 t1 t2).
+ Intros until 1; XElimUsing pc3_ind_left H; XEAuto.
+ Qed.
+
+ End csub0_pc3.
+
+ Hints Resolve csub0_pc3 : ltlc.
+
+ Section csub0_ty0. (*****************************************************)
+
+ Theorem csub0_ty0: (g:?; c1:?; t1,t2:?) (ty0 g c1 t1 t2) ->
+ (c2:?) (wf0 g c2) -> (csub0 g c1 c2) ->
+ (ty0 g c2 t1 t2).
+ Intros until 1; XElim H; Intros.
+(* case 1: ty0_conv *)
+ EApply ty0_conv; XEAuto.
+(* case 2: ty0_sort *)
+ XEAuto.
+(* case 3: ty0_abbr *)
+ CSub0Drop; EApply ty0_abbr; XEAuto.
+(* case 4: ty0_abst *)
+ CSub0Drop; [ EApply ty0_abst | EApply ty0_abbr ]; XEAuto.
+(* case 5: ty0_bind *)
+ EApply ty0_bind; XEAuto.
+(* case 6: ty0_appl *)
+ EApply ty0_appl; XEAuto.
+(* case 7: ty0_cast *)
+ EApply ty0_cast; XAuto.
+ Qed.
+
+ Theorem csub0_ty0_ld: (g:?; c:?; u,v:?) (ty0 g c u v) -> (t1,t2:?)
+ (ty0 g (CTail c (Bind Abst) v) t1 t2) ->
+ (ty0 g (CTail c (Bind Abbr) u) t1 t2).
+ Intros; EApply csub0_ty0; XEAuto.
+ Qed.
+
+ End csub0_ty0.
+
+ Hints Resolve csub0_ty0 csub0_ty0_ld : ltlc.
+
+ Tactic Definition CSub0Ty0 :=
+ Match Context With
+ [ _: (ty0 ?1 ?2 ?4 ?); _: (ty0 ?1 ?2 ?3 ?7); _: (pc3 ?2 ?4 ?7);
+ H: (ty0 ?1 (CTail ?2 (Bind Abst) ?4) ?5 ?6) |- ? ] ->
+ LApply (csub0_ty0_ld ?1 ?2 ?3 ?4); [ Intros H_x | EApply ty0_conv; XEAuto ];
+ LApply (H_x ?5 ?6); [ Clear H_x H; Intros | XAuto ].