On the cardinality of Hausdorff spaces

Alessandro Fedeli

Displaying similar documents to “On the cardinality of Hausdorff spaces”

On the cardinality of Hausdorff spaces.

Fedeli, A. (1998)

Commentationes Mathematicae Universitatis Carolinae

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Two cardinal inequalities for functionally Hausdorff spaces

Alessandro Fedeli (1994)

Commentationes Mathematicae Universitatis Carolinae

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In this paper, two cardinal inequalities for functionally Hausdorff spaces are established. A bound on the cardinality of the $τ θ$ -closed hull of a subset of a functionally Hausdorff space is given. Moreover, the following theorem is proved: if $X$ is a functionally Hausdorff space, then $| X | \leq 2^{χ (X) wcd (X)}$ .

Two set-theoretic problems in topology

Juhász, I.

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On the cardinality of n-Urysohn and n-Hausdorff spaces

Maddalena Bonanzinga, Maria Cuzzupé, Bruno Pansera (2014)

Open Mathematics

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Two variations of Arhangelskii’s inequality $|X| ⩽ 2^{χ (X) - L (X)}$ for Hausdorff X [Arhangel’skii A.V., The power of bicompacta with first axiom of countability, Dokl. Akad. Nauk SSSR, 1969, 187, 967–970 (in Russian)] given in [Stavrova D.N., Separation pseudocharacter and the cardinality of topological spaces, Topology Proc., 2000, 25(Summer), 333–343] are extended to the classes with finite Urysohn number or finite Hausdorff number.

Local cardinal functions of H-closed spaces

Angelo Bella, Jack R. Porter (1996)

Commentationes Mathematicae Universitatis Carolinae

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The cardinal functions of pseudocharacter, closed pseudocharacter, and character are used to examine H-closed spaces and to contrast the differences between H-closed and minimal Hausdorff spaces. An H-closed space $X$ is produced with the properties that $| X | > 2^{2^{ψ (X)}}$ and $\bar{ψ} (X) > 2^{ψ (X)}$ .