X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fmatita%2Flibrary%2Fnat%2Fplus.ma;h=79640b1362f86e9a654cc55a568d766daa8e0120;hb=8b55faddb06e3c4b0a13839210bb49170939b33e;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..79640b136 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.
@@ -67,8 +62,7 @@ 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.
 assumption.