If is a family of filters over some set I, a topological space X is sequencewise -compact if for every I-indexed sequence of elements of X there is such that the sequence has an F-limit point. Countable compactness, sequential compactness, initial κ-compactness, [λ; µ]-compactness, the Menger and Rothberger properties can all be expressed in terms of sequencewise -compactness for appropriate choices of . We show that sequencewise -compactness is preserved under taking products if and only if there is a filter such that sequencewise -compactness is equivalent to F-compactness. If this is the case, and there exists a sequencewise -compact T 1 topological space with more than one point, then F is necessarily an ultrafilter. The particular case of sequential compactness is analyzed in detail.

Lipparini, P. (2014). Topological spaces compact with respect to a set of filters. CENTRAL EUROPEAN JOURNAL OF MATHEMATICS, 12(7), 991-999 [10.2478/s11533-013-0398-2].

Topological spaces compact with respect to a set of filters

LIPPARINI, PAOLO
2014-01-01

Abstract

If is a family of filters over some set I, a topological space X is sequencewise -compact if for every I-indexed sequence of elements of X there is such that the sequence has an F-limit point. Countable compactness, sequential compactness, initial κ-compactness, [λ; µ]-compactness, the Menger and Rothberger properties can all be expressed in terms of sequencewise -compactness for appropriate choices of . We show that sequencewise -compactness is preserved under taking products if and only if there is a filter such that sequencewise -compactness is equivalent to F-compactness. If this is the case, and there exists a sequencewise -compact T 1 topological space with more than one point, then F is necessarily an ultrafilter. The particular case of sequential compactness is analyzed in detail.
2014
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore MAT/01 - LOGICA MATEMATICA
English
Con Impact Factor ISI
Filter; Ultrafilter convergence; Sequencewise -compactness; Preservation under products; Comfort pre-order; Sequential compactness
citato da (bibtex) @article {MR3231433, AUTHOR = {Brandhorst, Simon and Ern{\'e}, Marcel}, TITLE = {Tychonoff-like product theorems for local topological properties}, JOURNAL = {Topology Proc.}, FJOURNAL = {Topology Proceedings}, VOLUME = {45}, YEAR = {2015}, PAGES = {121--138}, ISSN = {0146-4124}, MRCLASS = {54B10 (06B35 54D30)}, MRNUMBER = {3231433}, MRREVIEWER = {Kyriakos Papadopoulos}, } e altre autocitazioni
http://www.degruyter.com/view/j/math.2014.12.issue-7/s11533-013-0398-2/s11533-013-0398-2.xml
Lipparini, P. (2014). Topological spaces compact with respect to a set of filters. CENTRAL EUROPEAN JOURNAL OF MATHEMATICS, 12(7), 991-999 [10.2478/s11533-013-0398-2].
Lipparini, P
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/90420
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