Bounds on the extent of a topological space

  • A. Ravsky Pidstryhach Institute for Applied Problems of Mechanics and Mathematics National Academy of Sciences of Ukraine Lviv, Ukraine
  • T. Banakh Ivan Franko National University of Lviv (Ukraine), and Jan Kochanowski University in Kielce (Poland)
Keywords: extent, cardinal topological characteristics, Lindelof number, spread, density

Abstract

The extent $e(X)$ of a topological space $X$ is the supremum of sizes of closed discrete subspaces of $X$. Assuming that $X$ belongs to some class of topological spaces, we bound $e(X)$ by
other cardinal characteristics of $X$, for instance Lindel\"of number, spread or density.

Author Biographies

A. Ravsky, Pidstryhach Institute for Applied Problems of Mechanics and Mathematics National Academy of Sciences of Ukraine Lviv, Ukraine

Pidstryhach Institute for Applied Problems of Mechanics and Mathematics
National Academy of Sciences of Ukraine
Lviv, Ukraine

T. Banakh, Ivan Franko National University of Lviv (Ukraine), and Jan Kochanowski University in Kielce (Poland)

Ivan Franko National University of Lviv (Ukraine), and Jan Kochanowski University in Kielce (Poland)

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Published
2022-03-31
How to Cite
Ravsky, A., & Banakh, T. (2022). Bounds on the extent of a topological space. Matematychni Studii, 57(1), 62-67. https://doi.org/10.30970/ms.57.1.62-67
Section
Articles