X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fmatita%2Flibrary%2Fnat%2Fplus.ma;h=d595dad19113cb6626ec4e58cc1e8a2d389be2b1;hb=97c2d258a5c524eb5c4b85208899d80751a2c82f;hp=8043d9a526663efc3b2b526fb35466cf49fe20be;hpb=fb94e5a71be508516514dfe50528ccfb3cd2da91;p=helm.git

diff --git a/helm/matita/library/nat/plus.ma b/helm/matita/library/nat/plus.ma
index 8043d9a52..d595dad19 100644
--- a/helm/matita/library/nat/plus.ma
+++ b/helm/matita/library/nat/plus.ma
@@ -43,7 +43,7 @@ simplify.rewrite > H.apply plus_n_Sm.
 qed.
 
 theorem associative_plus : associative nat plus.
-simplify.intros.elim x.
+unfold associative.intros.elim x.
 simplify.reflexivity.
 simplify.apply eq_f.assumption.
 qed.