proposition: Lemma filter_app : forall {A} (f: A -> _) s1 s2, List.filter f (s1 ++ s2) = List.filter f s1 ++ List.filter f s2.
proof: Proof. induction s1; simpl; intros. - reflexivity. - destruct (f a); simpl; congruence. Qed.
imports: Fiat.Common.Coq__8_4__8_5__Compat Coq.ZArith.ZArith Coq.Lists.List Coq.Lists.SetoidList Coq.Bool.Bool Fiat.Common Fiat.Common.List.Operations Fiat.Common.Equality Fiat.Common.List.FlattenList Fiat.Common.LogicFacts