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New rewrite rules image_iff
authorpaulson
Tue, 21 Oct 1997 10:36:23 +0200
changeset 3960 7a38fae985f9
parent 3959 033633d9a032
child 3961 6a8996fb7d99
New rewrite rules image_iff
src/HOL/Set.ML file | annotate | diff | comparison | revisions 
--- 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! ***)
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