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image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Acta Mathematica Hun...arrow_drop_down
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Acta Mathematica Hungarica
Article . 1996 . Peer-reviewed
License: Springer TDM
Data sources: Crossref
image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao
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Conditions implying continuity and perfectness of maps

Authors: Garg, G. L.; Goel, A.;

Conditions implying continuity and perfectness of maps

Abstract

Since every continuous map is compact-preserving, the question naturally arises, under what additional conditions a compact-preserving map becomes continuous. In [Proc. Am. Math. Soc. 11, 688-691 (1960; Zbl 0096.17002)] \textit{E. Halfar} investigated this problem for surjections between \(T_2\)-spaces. He proved that if \(X\) is locally compact then every compact-preserving map \(f:X\to Y\), which has closed fibers, is continuous. In [Pac. J. Math. 25, 495-509 (1968; Zbl 0165.25304)] \textit{R. V. Fuller} generalized Halfar's results. In [ibid. 59, 505-514 (1975; Zbl 0324.54007)] \textit{N. Liden} obtained the following generalization of Fuller's result: If \(X\) is a \(T_2\) \(k\)-space and \(Y\) is a \(KC\) space, then a surjection \(f:X\to Y\) is continuous iff \(f\) is compact-preserving and has closed fibers. In this paper the authors give analogues of Liden's theorem and obtain characterizations of perfect maps in terms of compact and compact-preserving maps. Examples are given to show that none of the conditions on the domain and range spaces in their theorems can be dropped. Simple alternatives to two complicated examples of Fuller [loc. cit.] and Halfar [loc. cit.] are also provided.

Keywords

Special maps on topological spaces (open, closed, perfect, etc.), Continuous maps

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
2
Average
Top 10%
Average
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