proposition: Lemma nbhs_filterE {T : Type} (F : set_system T) : nbhs F = F.
proof: Proof. by []. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed