--- a/src/Doc/Tutorial/Misc/Plus.thy Thu Jan 11 13:48:17 2018 +0100
+++ b/src/Doc/Tutorial/Misc/Plus.thy Fri Jan 12 14:08:53 2018 +0100
@@ -2,13 +2,13 @@
theory Plus imports Main begin
(*>*)
-text{*\noindent Define the following addition function *}
+text\<open>\noindent Define the following addition function\<close>
primrec add :: "nat \<Rightarrow> nat \<Rightarrow> nat" where
"add m 0 = m" |
"add m (Suc n) = add (Suc m) n"
-text{*\noindent and prove*}
+text\<open>\noindent and prove\<close>
(*<*)
lemma [simp]: "!m. add m n = m+n"
apply(induct_tac n)