| pos : nat \to Z
| neg : nat \to Z.
+interpretation "Integers" 'Z = Z.
+
definition Z_of_nat \def
\lambda n. match n with
[ O \Rightarrow OZ
| (S n)\Rightarrow pos n].
-coercion cic:/matita/Z/z/Z_of_nat.con.
+coercion Z_of_nat.
definition neg_Z_of_nat \def
\lambda n. match n with