proposition: Lemma filter_sort_le p s : filter p (sort <=%O s) = sort <=%O (filter p s).
proof: Proof. exact/filter_sort/le_trans/le_total. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)