The inequality |X| ≤2χ(X)has been proved to be true for Lindelöf spaces (Arhangel’ski˘ı, 1969), H-closed spaces (Dow-Porter, 1982) and ccc spaces (Hajnal-Juhász 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

A common extension of Lindelöf, H-closed and ccc

Bella, Angelo
2021

Abstract

The inequality |X| ≤2χ(X)has been proved to be true for Lindelöf spaces (Arhangel’ski˘ı, 1969), H-closed spaces (Dow-Porter, 1982) and ccc spaces (Hajnal-Juhász 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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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11769/514489
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