proposition: Lemma partition_neq0 P D B : partition P D -> B \in P -> B != set0.
proof: Proof. by move=> partP; apply: contraTneq => ->; rewrite (partition0 partP). Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop)