proposition: Lemma Ropp_Rmax : forall x y, - Rmax x y = Rmin (-x) (-y).
proof: Proof. intros x y; apply Rmax_case_strong. - now intros w; rewrite Rmin_left;[ | apply Rge_le, Ropp_le_ge_contravar]. - now intros w; rewrite Rmin_right; [ | apply Rge_le, Ropp_le_ge_contravar]. Qed.
imports: Rdefinitions Raxioms RIneq R_Ifp