proposition: Lemma le_sorted_eq s1 s2 : sorted <=%O s1 -> sorted <=%O s2 -> perm_eq s1 s2 -> s1 = s2.
proof: Proof. exact/sorted_eq/le_anti/le_trans. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)