diff -r 46f59511b7bb -r d97fdabd9e2b src/HOL/IMP/AExp.thy
--- a/src/HOL/IMP/AExp.thy	Fri Sep 20 19:07:10 2024 +0200
+++ b/src/HOL/IMP/AExp.thy	Fri Sep 20 19:51:08 2024 +0200
@@ -27,10 +27,10 @@
 
 text \<open>A little syntax magic to write larger states compactly:\<close>
 
-definition null_state ("<>") where
+definition null_state (\<open><>\<close>) where
   "null_state \<equiv> \<lambda>x. 0"
 syntax 
-  "_State" :: "updbinds => 'a" ("<_>")
+  "_State" :: "updbinds => 'a" (\<open><_>\<close>)
 translations
   "_State ms" == "_Update <> ms"
   "_State (_updbinds b bs)" <= "_Update (_State b) bs"