Metrizabillity of certain quotient space

Yoshio Tanaka

Displaying similar documents to “Metrizabillity of certain quotient space”

Mapping theorems on countable tightness and a question of F. Siwiec

Shou Lin, Jinhuang Zhang (2014)

Commentationes Mathematicae Universitatis Carolinae

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In this paper $s s$ -quotient maps and $s s q$ -spaces are introduced. It is shown that (1) countable tightness is characterized by $s s$ -quotient maps and quotient maps; (2) a space has countable tightness if and only if it is a countably bi-quotient image of a locally countable space, which gives an answer for a question posed by F. Siwiec in 1975; (3) $s s q$ -spaces are characterized as the $s s$ -quotient images of metric spaces; (4) assuming $2^{ω} < 2^{ω_{1}}$ , a compact $T_{2}$ -space is an $s s q$ -space if and only if every countably...

Accessibility spaces, $k$ -spaces and initial topologies

Charles E. Aull (1979)

Czechoslovak Mathematical Journal

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Two-fold theorem on Fréchetness of products

Szymon Dolecki, Tsugunori Nogura (1999)

Czechoslovak Mathematical Journal

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A refined common generalization of known theorems (Arhangel’skii, Michael, Popov and Rančin) on the Fréchetness of products is proved. A new characterization, in terms of products, of strongly Fréchet topologies is provided.