Kodai Mathematical Journal
Online ISSN : 1881-5472
Print ISSN : 0386-5991
ISSN-L : 0386-5991
A note on countably bi-quotient mappings
Shou LinZhongjing Zhu
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2012 Volume 35 Issue 2 Pages 392-402

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Abstract
In this paper some properties of weakly first countable spaces and sequence-covering images of metric spaces are studied. Strictly Fréchet spaces are characterized as the spaces in which every sequence-covering mapping onto them is strictly countably bi-quotient. Strict accessibility spaces are introduced, in which a T1-space X is strict accessibility if and only if every quotient mapping onto X is strictly countably bi-quotient. For a T2, k-space X every quotient mapping onto X is strictly countably bi-quotient or bi-quotient if and only if X is discrete. They partially answer some questions posed by F. Siwiec in [16, 17].
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© 2012 Department of Mathematics, Tokyo Institute of Technology
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