--- a/src/HOL/Analysis/Finite_Product_Measure.thy Wed Jan 10 15:21:49 2018 +0100
+++ b/src/HOL/Analysis/Finite_Product_Measure.thy Wed Jan 10 15:25:09 2018 +0100
@@ -929,7 +929,7 @@
using E by (subst insert) (auto intro!: prod.cong)
also have "(\<Prod>j\<in>I. if j \<in> J - {i} then emeasure (M j) (E j) else emeasure (M j) (space (M j))) *
emeasure (M i) (if i \<in> J then E i else space (M i)) = (\<Prod>j\<in>insert i I. ?f J E j)"
- using insert by (auto simp: mult.commute intro!: arg_cong2[where f="op *"] prod.cong)
+ using insert by (auto simp: mult.commute intro!: arg_cong2[where f="( * )"] prod.cong)
also have "\<dots> = (\<Prod>j\<in>J \<union> ?I. ?f J E j)"
using insert(1,2) J E by (intro prod.mono_neutral_right) auto
finally show "?\<mu> ?p = \<dots>" .