X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fmatita%2Flibrary%2Fnat%2Fplus.ma;h=d0038bac46f5c5cdebd51de3c2fc4152d6606072;hb=a79bf6edc13daaea8135ca71fdc92e02e229f030;hp=d595dad19113cb6626ec4e58cc1e8a2d389be2b1;hpb=55b82bd235d82ff7f0a40d980effe1efde1f5073;p=helm.git

diff --git a/helm/software/matita/library/nat/plus.ma b/helm/software/matita/library/nat/plus.ma
index d595dad19..d0038bac4 100644
--- a/helm/software/matita/library/nat/plus.ma
+++ b/helm/software/matita/library/nat/plus.ma
@@ -12,8 +12,6 @@
 (*                                                                        *)
 (**************************************************************************)
 
-set "baseuri" "cic:/matita/nat/plus".
-
 include "nat/nat.ma".
 
 let rec plus n m \def 
@@ -21,8 +19,7 @@ let rec plus n m \def
  [ O \Rightarrow m
  | (S p) \Rightarrow S (plus p m) ].
 
-(*CSC: the URI must disappear: there is a bug now *)
-interpretation "natural plus" 'plus x y = (cic:/matita/nat/plus/plus.con x y).
+interpretation "natural plus" 'plus x y = (plus x y).
 
 theorem plus_n_O: \forall n:nat. n = n+O.
 intros.elim n.
@@ -36,6 +33,11 @@ simplify.reflexivity.
 simplify.apply eq_f.assumption.
 qed.
 
+theorem plus_n_SO : \forall n:nat. S n = n+(S O).
+intro.rewrite > plus_n_O.
+apply plus_n_Sm.
+qed.
+
 theorem sym_plus: \forall n,m:nat. n+m = m+n.
 intros.elim n.
 simplify.apply plus_n_O.