diff -r 517aa9076fc9 -r b047339bd11c src/HOL/Option.thy --- a/src/HOL/Option.thy Sun Jun 17 13:10:14 2018 +0200 +++ b/src/HOL/Option.thy Sun Jun 17 20:31:51 2018 +0200 @@ -36,6 +36,9 @@ lemma not_Some_eq [iff]: "(\y. x \ Some y) \ x = None" by (induct x) auto +lemma comp_the_Some[simp]: "the o Some = id" +by auto + text \Although it may appear that both of these equalities are helpful only when applied to assumptions, in practice it seems better to give them the uniform iff attribute.\