--- a/src/ZF/nat.thy Tue Nov 16 14:23:19 1993 +0100
+++ b/src/ZF/nat.thy Tue Nov 16 14:24:21 1993 +0100
@@ -6,7 +6,7 @@
Natural numbers in Zermelo-Fraenkel Set Theory
*)
-Nat = Ord + Bool +
+Nat = Ord + Bool + "mono" +
consts
nat :: "i"
nat_case :: "[i, i=>i, i]=>i"