Čech-completeness and ultracompleteness in “nice spaces”

Miguel López de Luna; Vladimir Vladimirovich Tkachuk

Commentationes Mathematicae Universitatis Carolinae (2002)

  • Volume: 43, Issue: 3, page 515-524
  • ISSN: 0010-2628

Abstract

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We prove that if X n is a union of n subspaces of pointwise countable type then the space X is of pointwise countable type. If X ω is a countable union of ultracomplete spaces, the space X ω is ultracomplete. We give, under CH, an example of a Čech-complete, countably compact and non-ultracomplete space, giving thus a partial answer to a question asked in [BY2].

How to cite

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de Luna, Miguel López, and Tkachuk, Vladimir Vladimirovich. "Čech-completeness and ultracompleteness in “nice spaces”." Commentationes Mathematicae Universitatis Carolinae 43.3 (2002): 515-524. <http://eudml.org/doc/249005>.

@article{deLuna2002,
abstract = {We prove that if $X^n$ is a union of $n$ subspaces of pointwise countable type then the space $X$ is of pointwise countable type. If $X^\omega $ is a countable union of ultracomplete spaces, the space $X^\omega $ is ultracomplete. We give, under CH, an example of a Čech-complete, countably compact and non-ultracomplete space, giving thus a partial answer to a question asked in [BY2].},
author = {de Luna, Miguel López, Tkachuk, Vladimir Vladimirovich},
journal = {Commentationes Mathematicae Universitatis Carolinae},
keywords = {ultracompleteness; Čech-completeness; countable type; pointwise countable type; ultracomplete space; Čech-complete space; countable type; pointwise countable type; additive property},
language = {eng},
number = {3},
pages = {515-524},
publisher = {Charles University in Prague, Faculty of Mathematics and Physics},
title = {Čech-completeness and ultracompleteness in “nice spaces”},
url = {http://eudml.org/doc/249005},
volume = {43},
year = {2002},
}

TY - JOUR
AU - de Luna, Miguel López
AU - Tkachuk, Vladimir Vladimirovich
TI - Čech-completeness and ultracompleteness in “nice spaces”
JO - Commentationes Mathematicae Universitatis Carolinae
PY - 2002
PB - Charles University in Prague, Faculty of Mathematics and Physics
VL - 43
IS - 3
SP - 515
EP - 524
AB - We prove that if $X^n$ is a union of $n$ subspaces of pointwise countable type then the space $X$ is of pointwise countable type. If $X^\omega $ is a countable union of ultracomplete spaces, the space $X^\omega $ is ultracomplete. We give, under CH, an example of a Čech-complete, countably compact and non-ultracomplete space, giving thus a partial answer to a question asked in [BY2].
LA - eng
KW - ultracompleteness; Čech-completeness; countable type; pointwise countable type; ultracomplete space; Čech-complete space; countable type; pointwise countable type; additive property
UR - http://eudml.org/doc/249005
ER -

References

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  1. Arhangel'skiĭ A.V., Bicompact sets and the topology of spaces, Dokl. Akad. Nauk SSSR 150 (1963), 9-12. (1963) MR0150733
  2. Buhagiar D., Yoshioka I., Ultracomplete topological spaces, preprint. Zbl1019.54015MR1924245
  3. Buhagiar D., Yoshioka I., Sums and products of ultracomplete topological spaces, Topology Appl., to appear. Zbl1019.54015MR1919293
  4. Balogh Z, Gruenhage G., Tkachuk V., Additivity of metrizability and related properties, Topology Appl. (1998), 84 91-103. (1998) Zbl0991.54032MR1611277
  5. López de Luna M., Some new results on Čech-complete spaces, Topology Proceedings, vol.24, 1999. MR1876382
  6. Pasynkov B.A., Almost metrizable topological groups (in Russian), Dokl. Akad. Nauk SSSR (1965), 161.2 281-284. (1965) MR0204565
  7. Ponomarev V.I., Tkachuk V.V., The countable character of X in β X compared with the countable character of the diagonal in X × X , Vestnik Moskovskogo Universiteta, Matematika, 42 (1987), 5 16-19. (1987) Zbl0652.54003MR0913263
  8. Tkachuk V.V., Finite and countable additivity topological properties in nice spaces, Trans. Amer. Math. Soc. (1994), 341 585-601. (1994) MR1129438
  9. Tkachenko M.G., On a property of bicompacta, Seminar on General Topology, ed. by P.S. Alexandroff, Mosc. Univ. P.H., Moscow, 1981, pp.149-156. Zbl0491.54002MR0656955

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