| changeset 29691 | 9f03b5f847cd |
| parent 28562 | 4e74209f113e |
| child 29901 | f4b3f8fbf599 |
--- a/src/HOL/Set.thy Thu Jan 29 22:27:07 2009 +0100 +++ b/src/HOL/Set.thy Thu Jan 29 22:28:03 2009 +0100 @@ -885,6 +885,10 @@ "A = B ==> (!!x. x:B ==> C x = D x) ==> (UN x:A. C x) = (UN x:B. D x)" by (simp add: UNION_def) +lemma strong_UN_cong: + "A = B ==> (!!x. x:B =simp=> C x = D x) ==> (UN x:A. C x) = (UN x:B. D x)" + by (simp add: UNION_def simp_implies_def) + subsubsection {* Intersections of families *}