proposition: Lemma cardinal_inv_2b m : cardinal m <> 0 -> { p : key*elt | MapsTo (fst p) (snd p) m }.
proof: Proof. intros. generalize (@cardinal_inv_2 m); destruct cardinal. elim H;auto. eauto. Qed.
imports: Coq(Bool Equalities Orders OrdersFacts OrdersLists) Coq(Morphisms Permutation SetoidPermutation) MMaps(Utils Comparisons Interface)