proposition: Lemma Rmult_le_reg_r : forall r r1 r2, 0 < r -> r1 * r <= r2 * r -> r1 <= r2.
proof: Proof. intros r r1 r2 Hr I; rewrite 2(Rmult_comm _ r) in I. now apply (Rmult_le_reg_l r). Qed.
imports: RelationClasses Raxioms Rpow_def ZArith ZArithRing RealField