apply Mult.mult_le_compat_l; apply le_Nle; repeat rewrite N2Nat.id; auto.
Qed.

(* Specifications: *)
Theorem Nmult_ge_compat_l: forall n m p, n >= m -> p * n >= p * m.
intros n m p H1; apply Nge_ge; repeat rewrite N2Nat.inj_mul.