apply Rplus_eq_reg_l with a; auto.
Qed.

(* Specifications: *)
Theorem Rplus_ge_compat_l: forall n m p : R, (n >= m -> p + n >= p + m)%R.
intros n m p H; apply Rle_ge; apply Rplus_le_compat_l; auto; apply Rge_le; auto.