--- /dev/null
+(*#* #stop file *)
+
+Require subst1_defs.
+Require pr0_defs.
+Require pr0_subst0.
+
+ Section pr0_subst1_props. (***********************************************)
+
+ Theorem pr0_delta1: (u1,u2:?) (pr0 u1 u2) -> (t1,t2:?) (pr0 t1 t2) ->
+ (w:?) (subst1 (0) u2 t2 w) ->
+ (pr0 (TTail (Bind Abbr) u1 t1) (TTail (Bind Abbr) u2 w)).
+ Intros until 3; XElim H1; Clear w; XEAuto.
+ Qed.
+
+ Theorem pr0_subst1_back: (u2,t1,t2:?; i:?) (subst1 i u2 t1 t2) ->
+ (u1:?) (pr0 u1 u2) ->
+ (EX t | (subst1 i u1 t1 t) & (pr0 t t2)).
+ Intros until 1; XElim H; Intros;
+ Try Pr0Subst0; XEAuto.
+ Qed.
+
+ Theorem pr0_subst1_fwd: (u2,t1,t2:?; i:?) (subst1 i u2 t1 t2) ->
+ (u1:?) (pr0 u2 u1) ->
+ (EX t | (subst1 i u1 t1 t) & (pr0 t2 t)).
+ Intros until 1; XElim H; Intros;
+ Try Pr0Subst0; XEAuto.
+ Qed.
+
+ Theorem pr0_subst1: (t1,t2:?) (pr0 t1 t2) ->
+ (v1,w1:?; i:?) (subst1 i v1 t1 w1) ->
+ (v2:?) (pr0 v1 v2) ->
+ (EX w2 | (pr0 w1 w2) & (subst1 i v2 t2 w2)).
+ Intros until 2; XElim H0; Intros;
+ Try Pr0Subst0; XEAuto.
+ Qed.
+
+ End pr0_subst1_props.
+
+ Hints Resolve pr0_delta1 : ltlc.
+
+ Tactic Definition Pr0Subst1 :=
+ Match Context With
+ | [ H1: (pr0 ?1 ?2); H2: (subst1 ?3 ?4 ?1 ?5);
+ H3: (pr0 ?4 ?6) |- ? ] ->
+ LApply (pr0_subst1 ?1 ?2); [ Clear H1; Intros H1 | XAuto ];
+ LApply (H1 ?4 ?5 ?3); [ Clear H1 H2; Intros H1 | XAuto ];
+ LApply (H1 ?6); [ Clear H1; Intros H1 | XAuto ];
+ XElim H1; Intros
+ | [ H1: (pr0 ?1 ?2); H2: (subst1 ?3 ?4 ?1 ?5) |- ? ] ->
+ LApply (pr0_subst1 ?1 ?2); [ Clear H1; Intros H1 | XAuto ];
+ LApply (H1 ?4 ?5 ?3); [ Clear H1 H2; Intros H1 | XAuto ];
+ LApply (H1 ?4); [ Clear H1; Intros H1 | XAuto ];
+ XElim H1; Intros
+ | [ H1: (subst1 ?0 ?1 ?2 ?3); H2: (pr0 ?4 ?1) |- ? ] ->
+ LApply (pr0_subst1_back ?1 ?2 ?3 ?0); [ Clear H1; Intros H1 | XAuto ];
+ LApply (H1 ?4); [ Clear H1 H2; Intros H1 | XAuto ];
+ XElim H1; Intros
+ | [ H1: (subst1 ?0 ?1 ?2 ?3); H2: (pr0 ?1 ?4) |- ? ] ->
+ LApply (pr0_subst1_fwd ?1 ?2 ?3 ?0); [ Clear H1; Intros H1 | XAuto ];
+ LApply (H1 ?4); [ Clear H1 H2; Intros H1 | XAuto ];
+ XElim H1; Intros
+ | _ -> Pr0Subst0.
+