--- a/src/HOL/List.thy Thu Feb 19 10:37:15 2004 +0100
+++ b/src/HOL/List.thy Thu Feb 19 10:40:28 2004 +0100
@@ -1132,6 +1132,10 @@
"length a = length b \<Longrightarrow> (\<And>n. n < length a \<Longrightarrow> P (a!n) (b!n)) \<Longrightarrow> list_all2 P a b"
by (simp add: list_all2_conv_all_nth)
+lemma list_all2I:
+ "\<forall>x \<in> set (zip a b). split P x \<Longrightarrow> length a = length b \<Longrightarrow> list_all2 P a b"
+ by (simp add: list_all2_def)
+
lemma list_all2_nthD:
"\<lbrakk> list_all2 P xs ys; p < size xs \<rbrakk> \<Longrightarrow> P (xs!p) (ys!p)"
by (simp add: list_all2_conv_all_nth)