--- a/NEWS Thu Jun 01 12:08:33 2023 +0100
+++ b/NEWS Fri Jun 02 12:14:17 2023 +0200
@@ -237,6 +237,7 @@
fmember_iff_member_fset
notin_fset
- Added lemmas.
+ ffUnion_fsubset_iff
fimage_strict_mono
wfP_pfsubset
--- a/src/HOL/Library/FSet.thy Thu Jun 01 12:08:33 2023 +0100
+++ b/src/HOL/Library/FSet.thy Fri Jun 02 12:14:17 2023 +0200
@@ -1543,6 +1543,12 @@
done
+subsection \<open>Lemmas depending on induction\<close>
+
+lemma ffUnion_fsubset_iff: "ffUnion A |\<subseteq>| B \<longleftrightarrow> fBall A (\<lambda>x. x |\<subseteq>| B)"
+ by (induction A) simp_all
+
+
subsection \<open>Setup for Lifting/Transfer\<close>
subsubsection \<open>Relator and predicator properties\<close>