Hint Resolve Plt_succ: coqlib.

(* Specifications: *)
Lemma Plt_trans_succ:
forall (x y: positive), Plt x y -> Plt x (Pos.succ y).
Lemma Plt_succ_inv:
forall (x y: positive), Plt x (Pos.succ y) -> Plt x y \/ x = y.