Displaying similar documents to “On maps of spaces determined by countable subspaces”

Bi-quotient maps and cartesian products of quotient maps

Ernest Michael (1968)

Annales de l'institut Fourier

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Dans ce travail, on introduit une nouvelle classe d’applications, qui semble avoir beaucoup de propriétés désirables. En particulier, cette classe permet de donner une caractérisation des applications dont le produit cartésien avec une application quotient quelconque est toujours une application quotient.

Quotient Overrings

Hans H. Storrer (1973)

Publications du Département de mathématiques (Lyon)

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Natural covers

S. P. Franklin (1969)

Compositio Mathematica

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A-spaces and countably bi-quotient maps

E. Michael, R. C. Olson, F. Siwiec

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CONTENTS1. Introduction........................................................................................................................................................................... 52. Countably bi-quotient maps and their two generalizations......................................................................................... 93. Relatively pseudocompact and lightly compact subsets...............................................................................................

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...