--- 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 +