X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fground%2Flib%2Fsubset_equivalence.ma;h=622ee0f55a59563af0e9d61af28aa678c54fc873;hb=2e97c767bc072f5ba238725ff1f738fc91a0135a;hp=cddb51e89370ace7f4e6ce76ca712220e05d6a6d;hpb=80e953c112c66f884d167e7ff876c1f6289e1400;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/ground/lib/subset_equivalence.ma b/matita/matita/contribs/lambdadelta/ground/lib/subset_equivalence.ma
index cddb51e89..622ee0f55 100644
--- a/matita/matita/contribs/lambdadelta/ground/lib/subset_equivalence.ma
+++ b/matita/matita/contribs/lambdadelta/ground/lib/subset_equivalence.ma
@@ -56,3 +56,11 @@ theorem subset_eq_trans (A):
 #A #u1 #u2 * #H12 #H21 #u3 * #H23 #H32
 /3 width=5 by subset_le_trans, conj/
 qed-.
+
+theorem subset_eq_canc_sn (A):
+        left_cancellable … (subset_eq A).
+/3 width=3 by subset_eq_trans, subset_eq_sym/ qed-.
+
+theorem subset_eq_canc_dx (A):
+        right_cancellable … (subset_eq A).
+/3 width=3 by subset_eq_trans, subset_eq_sym/ qed-.