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