--- a/src/HOL/Library/Sublist.thy Wed Feb 14 11:51:03 2018 +0100
+++ b/src/HOL/Library/Sublist.thy Wed Feb 14 16:32:09 2018 +0100
@@ -147,6 +147,9 @@
lemma filter_mono_prefix: "prefix xs ys \<Longrightarrow> prefix (filter P xs) (filter P ys)"
by (auto simp: prefix_def)
+lemma sorted_antimono_prefix: "prefix xs ys \<Longrightarrow> sorted ys \<Longrightarrow> sorted xs"
+by (metis sorted_append prefix_def)
+
lemma prefix_length_less: "strict_prefix xs ys \<Longrightarrow> length xs < length ys"
by (auto simp: strict_prefix_def prefix_def)
@@ -526,6 +529,9 @@
lemma set_mono_suffix: "suffix xs ys \<Longrightarrow> set xs \<subseteq> set ys"
by (auto simp: suffix_def)
+lemma sorted_antimono_suffix: "suffix xs ys \<Longrightarrow> sorted ys \<Longrightarrow> sorted xs"
+by (metis sorted_append suffix_def)
+
lemma suffix_ConsD2: "suffix (x # xs) (y # ys) \<Longrightarrow> suffix xs ys"
proof -
assume "suffix (x # xs) (y # ys)"