--- a/src/HOL/Quickcheck_Examples/Hotel_Example.thy Sat Jan 13 11:22:46 2018 +0100
+++ b/src/HOL/Quickcheck_Examples/Hotel_Example.thy Sat Jan 13 11:42:30 2018 +0100
@@ -54,7 +54,7 @@
"roomk [] r = initk r"
| "roomk (e#s) r = (let k = roomk s r in
case e of Check_in g r' c \<Rightarrow> k
- | Enter g r' (x,y) \<Rightarrow> if r' = r (*& x = k*) then y else k
+ | Enter g r' (x,y) \<Rightarrow> if r' = r \<^cancel>\<open>\<and> x = k\<close> then y else k
| Exit g r \<Rightarrow> k)"
primrec isin :: "event list \<Rightarrow> room \<Rightarrow> guest set"