proposition: Lemma closed0 : closed set0.
proof: Proof. by move=> ? /(_ setT) [|? []] //; apply: filterT. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed