1.1 --- a/src/HOL/List.thy	Thu Feb 19 10:37:15 2004 +0100
     1.2 +++ b/src/HOL/List.thy	Thu Feb 19 10:40:28 2004 +0100
     1.3 @@ -1132,6 +1132,10 @@
     1.4    "length a = length b \<Longrightarrow> (\<And>n. n < length a \<Longrightarrow> P (a!n) (b!n)) \<Longrightarrow> list_all2 P a b"
     1.5    by (simp add: list_all2_conv_all_nth)
     1.6  
     1.7 +lemma list_all2I:
     1.8 +  "\<forall>x \<in> set (zip a b). split P x \<Longrightarrow> length a = length b \<Longrightarrow> list_all2 P a b"
     1.9 +  by (simp add: list_all2_def)
    1.10 +
    1.11  lemma list_all2_nthD:
    1.12    "\<lbrakk> list_all2 P xs ys; p < size xs \<rbrakk> \<Longrightarrow> P (xs!p) (ys!p)"
    1.13    by (simp add: list_all2_conv_all_nth)