proposition: Lemma Rmin_opp: forall x y, (Rmin (-x) (-y) = - Rmax x y)%R.
proof: Proof. intros x y. apply Rmax_case_strong; intros H. rewrite Rmin_left; trivial. now apply Ropp_le_contravar. rewrite Rmin_right; trivial. now apply Ropp_le_contravar. Qed.
imports: Coq(Psatz Reals ZArith) Zaux