proposition: Lemma Rplus_le_reg_r : forall r r1 r2, r1 + r <= r2 + r -> r1 <= r2.
proof: Proof. intros r r1 r2 H. now apply (Rplus_le_reg_l r); rewrite 2(Rplus_comm r). Qed.
imports: RelationClasses Raxioms Rpow_def ZArith ZArithRing RealField