--- a/src/HOL/MicroJava/DFA/Kildall.thy Tue Feb 13 14:24:50 2018 +0100
+++ b/src/HOL/MicroJava/DFA/Kildall.thy Thu Feb 15 12:11:00 2018 +0100
@@ -203,7 +203,7 @@
q \<notin> w \<or> q = p \<rbrakk>
\<Longrightarrow> stable r step (merges f (step p (ss!p)) ss) q"
apply (unfold stable_def)
- apply (subgoal_tac "\<forall>s'. (q,s') \<in> set (step p (ss!p)) \<longrightarrow> s' : A")
+ apply (subgoal_tac "\<forall>s'. (q,s') \<in> set (step p (ss!p)) \<longrightarrow> s' \<in> A")
prefer 2
apply clarify
apply (erule pres_typeD)