proposition: Lemma setpart_set1_eq_set1 (p : setpart [set x]) : p = setpart_set1.
proof: Proof. by case: p=> p Hp; apply/val_inj/part_set1_eq. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(div ssralg ssrint ssrnum binomial) tools combclass sorted ordtype partition