English

Star versions of Lindel\"of spaces

General Mathematics 2021-06-30 v3

Abstract

A space X X is said to be set star-Lindel\"{o}f (resp., set strongly star-Lindel\"{o}f) if for each nonempty subset A A of X X and each collection U \mathcal{U} of open sets in X X such that AU \overline{A} \subseteq \bigcup \mathcal{U} , there is a countable subset V \mathcal{V} of U \mathcal{U} (resp., countable subset F F of A \overline{A} ) such that ASt(V,U) A \subseteq {\rm St}( \bigcup \mathcal{V}, \mathcal{U}) (resp., ASt(F,U) A \subseteq {\rm St}( F, \mathcal{U})). The classes of set star-Lindel\"{o}f spaces and set strongly star-Lindel\"{o}f spaces lie between the class of Lindel\"{o}f spaces and the class of star-Lindel\"{o}f spaces. In this paper, we investigate the relationship among set star-Lindel\"{o}f spaces, set strongly star-Lindel\"{o}f spaces, and other related spaces by providing some suitable examples and study the topological properties of set star-Lindel\"{o}f and set strongly star-Lindel\"{o}f spaces.

Keywords

Cite

@article{arxiv.2007.01824,
  title  = {Star versions of Lindel\"of spaces},
  author = {Sumit Singh},
  journal= {arXiv preprint arXiv:2007.01824},
  year   = {2021}
}

Comments

14 pages. arXiv admin note: text overlap with arXiv:2006.15380