X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fdelayed_updating%2Fsyntax%2Fpath_proper.ma;h=66de8a4f6c37a0e4a3c869316c20f88690fbff93;hb=80e953c112c66f884d167e7ff876c1f6289e1400;hp=fca2eb91aae63a0d4f1b69d459df52cc54b98e05;hpb=d43c110267c05246b638e7f944e065820d5c1197;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/delayed_updating/syntax/path_proper.ma b/matita/matita/contribs/lambdadelta/delayed_updating/syntax/path_proper.ma
index fca2eb91a..66de8a4f6 100644
--- a/matita/matita/contribs/lambdadelta/delayed_updating/syntax/path_proper.ma
+++ b/matita/matita/contribs/lambdadelta/delayed_updating/syntax/path_proper.ma
@@ -35,10 +35,15 @@ qed.
 
 (* Basic inversions ********************************************************)
 
+lemma ppc_inv_empty:
+      (𝐞) ϵ 𝐏 → ⊥.
+#H0 @H0 -H0 //
+qed-.
+
 lemma ppc_inv_lcons (p):
       p ϵ 𝐏 → ∃∃l,q. l◗q = p.
 *
-[ #H elim H -H //
+[ #H0 elim (ppc_inv_empty … H0)
 | #l #q #_ /2 width=3 by ex1_2_intro/
 ]
 qed-.