diff -r cd32e6b34b5c -r 6c4421b006fb src/HOL/Data_Structures/Sorting.thy
--- a/src/HOL/Data_Structures/Sorting.thy	Mon Sep 10 20:48:22 2018 +0200
+++ b/src/HOL/Data_Structures/Sorting.thy	Mon Sep 10 21:33:14 2018 +0200
@@ -277,6 +277,9 @@
   "xss \<noteq> [] \<Longrightarrow> mset (merge_all xss) = (\<Union># (mset (map mset xss)))"
 by(induction xss rule: merge_all.induct) (auto simp: mset_merge mset_merge_adj)
 
+lemma mset_msort_bu: "mset (msort_bu xs) = mset xs"
+by(simp add: msort_bu_def mset_merge_all comp_def)
+
 lemma sorted_merge_adj:
   "\<forall>xs \<in> set xss. sorted xs \<Longrightarrow> \<forall>xs \<in> set (merge_adj xss). sorted xs"
 by(induction xss rule: merge_adj.induct) (auto simp: sorted_merge)
@@ -289,9 +292,6 @@
 lemma sorted_msort_bu: "sorted (msort_bu xs)"
 by(simp add: msort_bu_def sorted_merge_all)
 
-lemma mset_msort_bu: "mset (msort_bu xs) = mset xs"
-by(simp add: msort_bu_def mset_merge_all comp_def)
-
 
 subsubsection "Time Complexity"