proposition: Lemma oppr_max : {morph -%R : x y / max x y >-> min x y : R}.
proof: Proof. by move=> x y; apply: real_oppr_max. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)