proposition: Theorem zip_combine_eq : forall (A B : Set)(lsa : list A)(lsb : list B), zip lsa lsb = combine lsa lsb.
proof: Proof. induction lsa; intuition; simpl in *. destruct lsb; intuition. f_equal. eauto. Qed.
imports: FCF.Rat List Permutation Arith FCF.EqDec FCF.StdNat Bool Permutation