(** ** Remaining constants not defined in Stdlib.Init.Nat *)
(** NB: Aliasing [le] is mandatory, since only a Definition can implement an interface Parameter... *)
Definition eq := @Logic.eq nat.
Definition le := Peano.le.
Definition lt := Peano.lt.
(** ** Basic specifications : pred add sub mul *)

Lemma Even_2 n : Even n <-> Even (S (S n)).