X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fdelayed_updating%2Fsyntax%2Fpath_proper.ma;h=5d29633620eb9b15364d24f5177a28b8667db624;hb=306205b6853874cf485152222593b57249c6e7fa;hp=66de8a4f6c37a0e4a3c869316c20f88690fbff93;hpb=80e953c112c66f884d167e7ff876c1f6289e1400;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 66de8a4f6..5d2963362 100644
--- a/matita/matita/contribs/lambdadelta/delayed_updating/syntax/path_proper.ma
+++ b/matita/matita/contribs/lambdadelta/delayed_updating/syntax/path_proper.ma
@@ -29,8 +29,15 @@ interpretation
 
 (* Basic constructions ******************************************************)
 
-lemma ppc_lcons (l) (q): l◗q ϵ 𝐏.
-#l #p #H destruct
+lemma ppc_rcons (p) (l):
+      p◖l ϵ 𝐏.
+#p #l #H0 destruct
+qed.
+
+lemma ppc_lcons (p) (l):
+      l◗p ϵ 𝐏.
+#p #l #H0
+elim (eq_inv_list_empty_rcons ??? H0)
 qed.
 
 (* Basic inversions ********************************************************)
@@ -40,10 +47,18 @@ lemma ppc_inv_empty:
 #H0 @H0 -H0 //
 qed-.
 
-lemma ppc_inv_lcons (p):
-      p ϵ 𝐏 → ∃∃l,q. l◗q = p.
+lemma ppc_inv_rcons (p):
+      p ϵ 𝐏 → ∃∃q,l. q◖l = p.
 *
 [ #H0 elim (ppc_inv_empty … H0)
 | #l #q #_ /2 width=3 by ex1_2_intro/
 ]
 qed-.
+
+lemma ppc_inv_lcons (p):
+      p ϵ 𝐏 → ∃∃q,l. l◗q = p.
+#p @(list_ind_rcons … p) -p
+[ #H0 elim (ppc_inv_empty … H0)
+| #q #l #_ #_ /2 width=3 by ex1_2_intro/
+]
+qed-.