--- a/src/HOL/Data_Structures/Tree2.thy Fri Mar 18 08:32:37 2016 +0100
+++ b/src/HOL/Data_Structures/Tree2.thy Fri Mar 18 10:14:56 2016 +0100
@@ -14,4 +14,15 @@
"height Leaf = 0" |
"height (Node _ l a r) = max (height l) (height r) + 1"
+definition size1 :: "('a,'b) tree \<Rightarrow> nat" where
+"size1 t = size t + 1"
+
+lemma size1_simps[simp]:
+ "size1 \<langle>\<rangle> = 1"
+ "size1 \<langle>u, l, x, r\<rangle> = size1 l + size1 r"
+by (simp_all add: size1_def)
+
+lemma size1_ge0[simp]: "0 < size1 t"
+by (simp add: size1_def)
+
end