X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fground%2Flib%2Fsubset_ext_equivalence.ma;h=28e4facc8fada42dea5249abc964c86f9f87a6e3;hb=538c84b5b1129b34c051c364fdd304f52714482c;hp=f20aca24fc2903e33d300817be8825d7d15800e8;hpb=f2a1fcef1f05dae5dff517ffc0a8439f6071955b;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/ground/lib/subset_ext_equivalence.ma b/matita/matita/contribs/lambdadelta/ground/lib/subset_ext_equivalence.ma
index f20aca24f..28e4facc8 100644
--- a/matita/matita/contribs/lambdadelta/ground/lib/subset_ext_equivalence.ma
+++ b/matita/matita/contribs/lambdadelta/ground/lib/subset_ext_equivalence.ma
@@ -19,8 +19,18 @@ include "ground/lib/subset_equivalence.ma".
 
 (* Constructions with subset_equivalence ************************************)
 
+lemma subset_equivalence_ext_f1_exteq (A1) (A0) (f1) (f2) (u):
+      f1 ⊜ f2 → subset_ext_f1 A1 A0 f1 u ⇔ subset_ext_f1 A1 A0 f2 u.
+/3 width=3 by subset_inclusion_ext_f1_exteq, conj/
+qed.
+
 lemma subset_equivalence_ext_f1_bi (A1) (A0) (f) (u1) (v1):
       u1 ⇔ v1 → subset_ext_f1 A1 A0 f u1 ⇔ subset_ext_f1 A1 A0 f v1.
 #A1 #A0 #f #u1 #v1 * #Huv1 #Hvu1
 /3 width=3 by subset_inclusion_ext_f1_bi, conj/
 qed.
+
+lemma subset_inclusion_ext_f1_compose (A0) (A1) (A2) (f1) (f2) (u):
+      subset_ext_f1 A1 A2 f2 (subset_ext_f1 A0 A1 f1 u) ⇔ subset_ext_f1 A0 A2 (f2∘f1) u.
+/3 width=1 by subset_inclusion_ext_f1_compose_dx, subset_inclusion_ext_f1_compose_sn, conj/
+qed.