diff -r cc0b3e177b49 -r 60b924cda764 src/HOL/Isar_Examples/Group.thy
--- a/src/HOL/Isar_Examples/Group.thy	Fri Mar 01 21:29:59 2019 +0100
+++ b/src/HOL/Isar_Examples/Group.thy	Sun Mar 03 16:00:14 2019 +0100
@@ -12,8 +12,8 @@
 
 text \<open>
   Groups over signature \<open>(* :: \<alpha> \<Rightarrow> \<alpha> \<Rightarrow> \<alpha>, 1 :: \<alpha>, inverse :: \<alpha> \<Rightarrow> \<alpha>)\<close> are
-  defined as an axiomatic type class as follows. Note that the parent class
-  \<open>times\<close> is provided by the basic HOL theory.
+  defined as an axiomatic type class as follows. Note that the parent classes
+  \<^class>\<open>times\<close>, \<^class>\<open>one\<close>, \<^class>\<open>inverse\<close> is provided by the basic HOL theory.
 \<close>
 
 class group = times + one + inverse +