We try to find a common extension of two cardinal inequalities for Lindelof spaces. Using an estimate of the number of G(delta) points due to Balogh, we improve a result of Juhasz and Spadaro. A cardinal inequality for linearly Lindelof Tychonoff spaces proved by Arhangel'skii and Buzyakova should be actually true for Hausdorff spaces. We observe this happens under some restrictions on cardinal arithmetics, including a consequence of Martin's axiom. Finally, we address the question to estimate the cardinality of a first countable linearly H-closed space

Observations on some cardinality bounds

BELLA, Angelo
2017-01-01

Abstract

We try to find a common extension of two cardinal inequalities for Lindelof spaces. Using an estimate of the number of G(delta) points due to Balogh, we improve a result of Juhasz and Spadaro. A cardinal inequality for linearly Lindelof Tychonoff spaces proved by Arhangel'skii and Buzyakova should be actually true for Hausdorff spaces. We observe this happens under some restrictions on cardinal arithmetics, including a consequence of Martin's axiom. Finally, we address the question to estimate the cardinality of a first countable linearly H-closed space
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/304284
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