请输入您要查询的百科知识:

 

词条 Locally normal space
释义

  1. Formal definition

  2. Examples and properties

  3. See also

  4. References

{{Unreferenced|date=July 2008}}

In mathematics, particularly topology, a topological space X is locally normal if intuitively it looks locally like a normal space. More precisely, a locally normal space satisfies the property that each point of the space belongs to a neighbourhood of the space that is normal under the subspace topology.

Formal definition

A topological space X is said to be locally normal if and only if each point, x, of X has a neighbourhood that is normal under the subspace topology.

Note that not every neighbourhood of x has to be normal, but at least one neighbourhood of x has to be normal (under the subspace topology).

Note however, that if a space were called locally normal if and only if each point of the space belonged to a subset of the space that was normal under the subspace topology, then every topological space would be locally normal. This is because, the singleton {x} is vacuously normal and contains x. Therefore, the definition is more restrictive.

Examples and properties

  • Every locally normal T1 space is locally regular and locally Hausdorff.
  • A locally compact Hausdorff space is always locally normal.
  • A normal space is always locally normal.
  • A T1 space need not be locally normal as the set of all real numbers endowed with the cofinite topology shows.

See also

  • Locally Hausdorff space
  • Locally compact space
  • Locally metrizable space
  • Normal space
  • Homeomorphism
  • Locally regular space

References

{{Topology-stub}}

2 : Topology|Properties of topological spaces

随便看

 

开放百科全书收录14589846条英语、德语、日语等多语种百科知识,基本涵盖了大多数领域的百科知识,是一部内容自由、开放的电子版国际百科全书。

 

Copyright © 2023 OENC.NET All Rights Reserved
京ICP备2021023879号 更新时间:2024/11/16 12:18:15