proposition: Lemma interior_subset (A : set T) : A^° `<=` A.
proof: Proof. by move=> p; rewrite /interior nbhsE => -[? [? ?]]; apply. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed