proposition: Lemma pblock_trivsetpart x : x \in S -> pblock trivsetpart x = S.
proof: Proof. move=> xinS. apply: (def_pblock (trivIsetpart _)); rewrite ?inE //. rewrite /trivsetpart /=. suff /negbTE -> : S != set0 by rewrite inE. by apply/set0Pn; exists x. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(div ssralg ssrint ssrnum binomial) tools combclass sorted ordtype partition