X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fmatita%2Flibrary%2FZ%2Fz.ma;h=ac530c38fe02b7df1766fd69ff93a637162131b0;hb=4c5f91917b06e323411981a22142bfedba996518;hp=d8b829ec1da6e60da84bf89fe20c94e80dc72351;hpb=576a1f3f67dc0207a664a127fe482facbfa2a826;p=helm.git

diff --git a/helm/software/matita/library/Z/z.ma b/helm/software/matita/library/Z/z.ma
index d8b829ec1..ac530c38f 100644
--- a/helm/software/matita/library/Z/z.ma
+++ b/helm/software/matita/library/Z/z.ma
@@ -34,6 +34,11 @@ definition neg_Z_of_nat \def
 [ O \Rightarrow  OZ 
 | (S n)\Rightarrow  neg n].
 
+lemma pos_n_eq_S_n : \forall n : nat.
+  (pos n) = (S n).
+intro.reflexivity. 
+qed.
+
 definition abs \def
 \lambda z.
  match z with 
@@ -117,7 +122,7 @@ elim x.
   (* goal: x=pos y=pos *)
     elim (decidable_eq_nat n n1:((n=n1) \lor ((n=n1) \to False))).
     left.apply eq_f.assumption.
-    right.unfold Not.intros (H_inj).apply H. destruct H_inj. assumption.
+    right.unfold Not.intros (H_inj).apply H. destruct H_inj. reflexivity.
   (* goal: x=pos y=neg *)
     right.unfold Not.intro.apply (not_eq_pos_neg n n1). assumption.
 (* goal: x=neg *)