diff -r 91c00d8f1bdd -r d60c3f1ba86f src/HOL/Library/Multiset.thy
--- a/src/HOL/Library/Multiset.thy	Tue Mar 04 13:10:47 2025 +0100
+++ b/src/HOL/Library/Multiset.thy	Tue Mar 04 15:19:08 2025 +0100
@@ -1745,7 +1745,7 @@
      image_mset f (filter_mset P A) + image_mset g (filter_mset (\<lambda>x. \<not>P x) A)"
   by (induction A) auto
 
-lemma filter_image_mset:
+lemma filter_mset_image_mset:
   "filter_mset P (image_mset f A) = image_mset f (filter_mset (\<lambda>x. P (f x)) A)"
   by (induction A) auto