proposition: Lemma Rplus_gt_compat : forall r1 r2 r3 r4, r1 > r2 -> r3 > r4 -> r1 + r3 > r2 + r4.
proof: Proof. now intros r1 r2 r3 r4; apply Rplus_lt_compat. Qed.
imports: RelationClasses Raxioms Rpow_def ZArith ZArithRing RealField