proposition: Lemma le_enum_rank : {mono enum_rank : i j / i <= j}.
proof: Proof. exact: can_mono enum_rankK (@le_enum_val predT). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)