proposition: Lemma nbhs_subspace_in (x : T) : A x -> within A (nbhs x) = nbhs_subspace x.
proof: Proof. by case: nbhs_subspaceP_subproof. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed