X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fdelayed_updating%2Fsubstitution%2Flift_prototerm.ma;h=4a0615a3ca081265e256e54a4cb683ef7810e351;hb=13584a37bbcde10e03c8a488f5b93e1e042da0a6;hp=9193260452841583ff83da63e3f76f9c72a68ff5;hpb=2cc4eb5d0210be58286e028278852122dcb68052;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/delayed_updating/substitution/lift_prototerm.ma b/matita/matita/contribs/lambdadelta/delayed_updating/substitution/lift_prototerm.ma
index 919326045..4a0615a3c 100644
--- a/matita/matita/contribs/lambdadelta/delayed_updating/substitution/lift_prototerm.ma
+++ b/matita/matita/contribs/lambdadelta/delayed_updating/substitution/lift_prototerm.ma
@@ -26,4 +26,10 @@ interpretation
 
 lemma in_comp_lift_bi (f) (p) (t):
       p ϵ t → ↑[f]p ϵ ↑[f]t.
-/2 width=1 by subset_in_ext_f1_dx/ qed.
+/2 width=1 by subset_in_ext_f1_dx/
+qed.
+
+lemma eq_lift_bi (f) (t1) (t2):
+      t1 ⇔ t2 → ↑[f]t1 ⇔ ↑[f]t2.
+/2 width=1 by subset_equivalence_ext_f1_bi/
+qed.