proposition: Lemma comparable_max_idPl : reflect (max x y = x) (y <= x).
proof: Proof. by apply: (iffP idP); rewrite (rwP eqP) comparable_eq_maxl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)