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arXiv · 2002.02719

A common extension of Lindelöf, H-closed and ccc

Angelo Bella
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Abstract

The inequality $|X| \leq 2^{χ(X)}$ has been proved to be true for Lindelöf spaces (Arhangel'ski\uı, 1969), $H$-closed spaces (Dow-Porter, 1982) and ccc spaces (Hajnal-Juász 1967), by quite different arguments. We present a common extension of all these properties which allows us to give a unified proof of these three theorems.

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Angelo Bella. 2020-02-07. A common extension of Lindelöf, H-closed and ccc. https://arxiv.org/abs/2002.02719

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