--- a/thys/Exercises.thy	Thu Dec 07 12:45:22 2017 +0000
+++ b/thys/Exercises.thy	Fri Jan 12 02:33:35 2018 +0000
@@ -75,6 +75,10 @@
       (\<not> zeroable r1 \<and> infinitestrings r2) \<or> (\<not> zeroable r2 \<and> infinitestrings r1)"
 | "infinitestrings (STAR r) = (\<not> atmostempty r)"
 
+
+
+
+
 lemma Star_atmostempty:
   assumes "A \<subseteq> {[]}"
   shows "A\<star> \<subseteq> {[]}"