src/HOL/Set.ML
changeset 3960 7a38fae985f9
parent 3919 c036caebfc75
child 4059 59c1422c9da5
--- a/src/HOL/Set.ML	Mon Oct 20 17:21:54 1997 +0200
+++ b/src/HOL/Set.ML	Tue Oct 21 10:36:23 1997 +0200
@@ -623,6 +623,10 @@
 by (Blast_tac 1);
 qed "image_Un";
 
+goal Set.thy "(z : f``A) = (EX x:A. z = f x)";
+by (Blast_tac 1);
+qed "image_iff";
+
 
 (*** Range of a function -- just a translation for image! ***)