Zero-dimensional space
Topological space of dimension zero
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Through Mathematics, Dimension and Point (geometry)
Definition
Specifically:
- A topological space is zero-dimensional with respect to the Lebesgue covering dimension if every open cover of the space has a refinement that is a cover by disjoint open sets.
- A topological space is zero-dimensional with respect to the finite-to-finite covering dimension if every finite open cover of the space has a refinement that is a finite open cover such that any point in the space is contained in exactly one open set of this refinement.
- A topological space is zero-dimensional with respect to the small inductive dimension if it has a base consisting of clopen sets.
The three notions above agree for separable, metrisable spaces (see Inductive dimension § Relationships between dimensions).
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Properties of spaces with small inductive dimension zero
- A zero-dimensional Hausdorff space is necessarily totally disconnected, but the converse fails. However, a locally compact Hausdorff space is zero-dimensional if and only if it is totally disconnected. (See (Arhangel'skii & Tkachenko 2008, Proposition 3.1.7, p.136) for the non-trivial direction.)
- Zero-dimensional Polish spaces are a particularly convenient setting for descriptive set theory. Examples of such spaces include the Cantor space and Baire space.
- Hausdorff zero-dimensional spaces are precisely the subspaces of topological powers where is given the discrete topology. Such a space is sometimes called a Cantor cube. If I is countably infinite, is the Cantor space.
Manifolds
More in Geometry
Euclidean spaceFundamental space of geometryCartesian coordinate systemCoordinate system using perpendicular axesSphereSet of points equidistant from a centerTopological spaceMathematical space with a notion of closenessManifoldTopological space that locally resembles Euclidean spaceMetric spaceMathematical space with a notion of distance

