# HG changeset patch
# User Christian Urban <christian dot urban at kcl dot ac dot uk>
# Date 1452698534 0
# Node ID 3fa70b12c1177440db2d5b51e5e3d5ebb6bb60b1
# Parent  04caf0ccb3aeb4685b728e8a93c8bc0f38e57fdd
another simplification

diff -r 04caf0ccb3ae -r 3fa70b12c117 Moment.thy
--- a/Moment.thy	Wed Jan 13 15:16:59 2016 +0000
+++ b/Moment.thy	Wed Jan 13 15:22:14 2016 +0000
@@ -146,9 +146,8 @@
 lemma moment_Suc_tl:
   assumes "Suc i \<le> length s"
   shows "tl (moment (Suc i) s) = moment i s"
-  using assms unfolding moment_def
-sorry
-
+  using assms unfolding moment_def rev_take
+by (simp, metis Suc_diff_le diff_Suc_Suc drop_Suc tl_drop)
 
 lemma moment_plus:
   assumes "Suc i \<le> length s"