| (pos n) \Rightarrow (neg (pred (times (S m) (S n))))
| (neg n) \Rightarrow (pos (pred (times (S m) (S n))))]].
-theorem Ztimes_z_OZ: \forall z:Z. eq Z (Ztimes z OZ) OZ.
+(*CSC: the URI must disappear: there is a bug now *)
+interpretation "integer times" 'times x y = (cic:/matita/Z/times/Ztimes.con x y).
+
+theorem Ztimes_z_OZ: \forall z:Z. z*OZ = OZ.
intro.elim z.
simplify.reflexivity.
simplify.reflexivity.
simplify.reflexivity.
qed.
-
+(*CSC: da qui in avanti niente notazione *)
(*
theorem symmetric_Ztimes : symmetric Z Ztimes.
change with \forall x,y:Z. eq Z (Ztimes x y) (Ztimes y x).
variant assoc_Zplus : \forall x,y,z:Z. eq Z (Zplus (Zplus x y) z) (Zplus x (Zplus y z))
\def associative_Zplus.
-
-definition Zopp : Z \to Z \def
-\lambda x:Z. match x with
-[ OZ \Rightarrow OZ
-| (pos n) \Rightarrow (neg n)
-| (neg n) \Rightarrow (pos n) ].
-
-theorem Zplus_Zopp: \forall x:Z. (eq Z (Zplus x (Zopp x)) OZ).
-intro.elim x.
-apply refl_eq.
-simplify.
-rewrite > nat_compare_n_n.
-simplify.apply refl_eq.
-simplify.
-rewrite > nat_compare_n_n.
-simplify.apply refl_eq.
-qed.
*)