simpl in H; elim minus_n_O; assumption.
elim H0.
elim plus_comm; rewrite plus_opp; auto with arith.
intros.
simpl in |- *; apply H; auto with arith.
Qed.
Hint Resolve le_transp_l.

(* Specifications: *)
Lemma le_transp_r : forall n m p : nat, n + m <= p -> n <= p - m.
intros.