proposition: Lemma Rle_lt_dec : forall r1 r2, {r1 <= r2} + {r2 < r1}.
proof: Proof. intros r1 r2; destruct (Rle_dec r1 r2) as [Hle | H%Rnot_le_lt]. - now left. - now right. Qed.
imports: RelationClasses Raxioms Rpow_def ZArith ZArithRing RealField