fix set theories diff definition

6a4b3aa2 · François Bobot · 7b710749 · 6a4b3aa2
Commit 6a4b3aa2 authored May 11, 2011 by François Bobot
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theories/set.why theories/set.why +1 -1

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--- a/theories/set.why
+++ b/theories/set.why
@@ -114,7 +114,7 @@ theory SetMap

  axiom Diff_def1 :
    forall s1 s2 : set 'a. forall x : 'a.
-    (diff s1 s2)[x] = xorb s1[x] s2[x]
+    (diff s1 s2)[x] = andb s1[x] (notb s2[x])

  logic equal(s1 s2 : set 'a) = forall x : 'a. s1[x] = s2[x]