X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fmatita%2Flibrary%2Fnat%2Fplus.ma;h=d595dad19113cb6626ec4e58cc1e8a2d389be2b1;hb=97c2d258a5c524eb5c4b85208899d80751a2c82f;hp=1c145dd6141cea519fd99f7c681a179159a72346;hpb=71590f4a0cb620a5e98fee3e8d65670271234532;p=helm.git

diff --git a/helm/matita/library/nat/plus.ma b/helm/matita/library/nat/plus.ma
index 1c145dd61..d595dad19 100644
--- a/helm/matita/library/nat/plus.ma
+++ b/helm/matita/library/nat/plus.ma
@@ -36,11 +36,6 @@ simplify.reflexivity.
 simplify.apply eq_f.assumption.
 qed.
 
-(* some problem here: confusion between relations/symmetric 
-and functions/symmetric; functions symmetric is not in 
-functions.moo why?
-theorem symmetric_plus: symmetric nat plus. *)
-
 theorem sym_plus: \forall n,m:nat. n+m = m+n.
 intros.elim n.
 simplify.apply plus_n_O.
@@ -48,7 +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.
@@ -67,10 +62,9 @@ theorem inj_plus_r: \forall p,n,m:nat. p+n = p+m \to n=m
 
 theorem injective_plus_l: \forall m:nat.injective nat nat (\lambda n.n+m).
 intro.simplify.intros.
-(* qui vorrei applicare injective_plus_r *)
-apply inj_plus_r m.
+apply (injective_plus_r m).
 rewrite < sym_plus.
-rewrite < sym_plus y.
+rewrite < (sym_plus y).
 assumption.
 qed.