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 spaceFile in questo prodotto:
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