proposition: Lemma nbhsx_ballx (x : M) (eps : R) : 0 < eps -> nbhs x (ball x eps).
proof: Proof. by move=> e0; apply/nbhs_ballP; exists eps. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed