- basics: some support for abstract triangular confluence (which

[helm.git] / matita / matita / lib / basics / star.ma

diff --git a/matita/matita/lib/basics/star.ma b/matita/matita/lib/basics/star.ma
index bac2e771c23672b73fa9d936dc5fac913d3ac461..bff1aaeef80042a2ae2e838317d0c5ed5c858a58 100644 (file)
--- a/matita/matita/lib/basics/star.ma
+++ b/matita/matita/lib/basics/star.ma
@@ -191,3 +191,10 @@ lemma TC_star_ind_dx: ∀A,R. reflexive A R →
 #A #R #HR #a2 #P #Ha2 #H #a1 #Ha12
 @(TC_star_ind_dx_aux … HR … Ha2 H … Ha12) //
 qed-.
+
+definition Conf3: ∀A. relation A → relation A → Prop ≝ λA,S,R.
+                  ∀a,a1. S a1 a → ∀a2. R a1 a2 → S a2 a.
+
+lemma TC_Conf3: ∀A,S,R. Conf3 A S R → Conf3 A S (TC … R).
+#A #S #R #HSR #a #a1 #Ha1 #a2 #H elim H -a2 /2 width=3/
+qed.