X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;ds=sidebyside;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fdelayed_updating%2Fsyntax%2Fpath_proper.ma;h=9cab60b87950a5c132f82f4bbf1361a723d5e61c;hb=97ff918432e878ab8314c72fe2b948a253b26e21;hp=fca2eb91aae63a0d4f1b69d459df52cc54b98e05;hpb=13584a37bbcde10e03c8a488f5b93e1e042da0a6;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..9cab60b87 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 +35,23 @@ 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-.
+
+lemma ppc_inv_rcons (p):
+      p ϵ 𝐏 → ∃∃q,l. q◖l = p.
+#p @(list_ind_rcons … p) -p
+[ #H0 elim (ppc_inv_empty … H0)
+| #q #l #_ #_ /2 width=3 by ex1_2_intro/
+]
+qed-.