diff -r 32d2b96affc7 -r 200107cdd3ac src/HOL/Analysis/Nonnegative_Lebesgue_Integration.thy
--- a/src/HOL/Analysis/Nonnegative_Lebesgue_Integration.thy	Sun May 05 15:31:08 2024 +0100
+++ b/src/HOL/Analysis/Nonnegative_Lebesgue_Integration.thy	Mon May 06 14:39:33 2024 +0100
@@ -713,7 +713,7 @@
       then have "0 < ?M"
         by (simp add: less_le)
       also have "\<dots> \<le> ?\<mu> (\<lambda>y. f x \<le> g x)"
-        using mono by (intro emeasure_mono_AE) auto
+        using mono by (force intro: emeasure_mono_AE) 
       finally have "\<not> \<not> f x \<le> g x"
         by (intro notI) auto
       then show ?thesis