proposition: Lemma Rmult_lt_compat_r : forall r r1 r2, 0 < r -> r1 < r2 -> r1 * r < r2 * r.
proof: Proof. intros r r1 r2; rewrite 2(Rmult_comm _ r); apply Rmult_lt_compat_l. Qed.
imports: RelationClasses Raxioms Rpow_def ZArith ZArithRing RealField