First countable and countable spaces all compactifications of which contain βN
Eric van Douwen, Teodor Przymusiński (1979)
Fundamenta Mathematicae
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Eric van Douwen, Teodor Przymusiński (1979)
Fundamenta Mathematicae
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Angelo Bella, Viacheslav I. Malykhin (1998)
Commentationes Mathematicae Universitatis Carolinae
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We prove resolvability and maximal resolvability of topological spaces having countable tightness with some additional properties. For this purpose, we introduce some new versions of countable tightness. We also construct a couple of examples of irresolvable spaces.
Baboolal, D., Backhouse, J., Ori, R.G. (1990)
International Journal of Mathematics and Mathematical Sciences
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Ofelia Alas, Lucia Junqueira, Jan Mill, Vladimir Tkachuk, Richard Wilson (2011)
Open Mathematics
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For a topological property P, we say that a space X is star Pif for every open cover Uof the space X there exists Y ⊂ X such that St(Y,U) = X and Y has P. We consider star countable and star Lindelöf spaces establishing, among other things, that there exists first countable pseudocompact spaces which are not star Lindelöf. We also describe some classes of spaces in which star countability is equivalent to countable extent and show that a star countable space with a dense σ-compact subspace...
P. Moody, G. Reed, A. Roscoe, P. Collins (1991)
Fundamenta Mathematicae
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Aleksander V. Arhangel'skii (2010)
Commentationes Mathematicae Universitatis Carolinae
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Some strong versions of the Fréchet-Urysohn property are introduced and studied. We also strengthen the concept of countable tightness and generalize the notions of first-countability and countable base. A construction of a topological space is described which results, in particular, in a Tychonoff countable Fréchet-Urysohn space which is not first-countable at any point. It is shown that this space can be represented as the image of a countable metrizable space under a continuous pseudoopen...
Eric van Douwen, Teodor Przymusiński (1980)
Fundamenta Mathematicae
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