Bounds on the extent of a topological space

A. Ravsky; T. Banakh

doi:10.30970/ms.57.1.62-67

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)

DOI: https://doi.org/10.30970/ms.57.1.62-67

Анотація

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.

Біографії авторів

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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