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On Eberlein compactifications of metrizable spaces

Takashi Kimura, Kazuhiko Morishita (2002)

Fundamenta Mathematicae

We prove that, for every finite-dimensional metrizable space, there exists a compactification that is Eberlein compact and preserves both the covering dimension and weight.

On extension of the group operation over the Čech-Stone compactification

Jan Jełowicki (1993)

Colloquium Mathematicae

The convolution of ultrafilters of closed subsets of a normal topological group is considered as a substitute of the extension onto ( β ) 2 of the group operation. We find a subclass of ultrafilters for which this extension is well-defined and give some examples of pathologies. Next, for a given locally compact group and its dense subgroup , we construct subsets of β algebraically isomorphic to . Finally, we check whether the natural mapping from β onto β is a homomorphism with respect to the extension...

On finest unitary extensions of topological monoids

Boris G. Averbukh (2015)

Topological Algebra and its Applications

We prove that the Wyler completion of the unitary Cauchy space on a given Hausdorff topological 5 monoid consisting of the underlying set of this monoid and of the family of unitary Cauchy filters on it, is a T2-topological space and, in the commutative case, an abstract monoid containing the initial one.

On hereditary normality of ω * , Kunen points and character ω 1

Sergei Logunov (2021)

Commentationes Mathematicae Universitatis Carolinae

We show that ω * { p } is not normal, if p is a limit point of some countable subset of ω * , consisting of points of character ω 1 . Moreover, such a point p is a Kunen point and a super Kunen point.

On non-normality points, Tychonoff products and Suslin number

Sergei Logunov (2022)

Commentationes Mathematicae Universitatis Carolinae

Let a space X be Tychonoff product α < τ X α of τ -many Tychonoff nonsingle point spaces X α . Let Suslin number of X be strictly less than the cofinality of τ . Then we show that every point of remainder is a non-normality point of its Čech–Stone compactification β X . In particular, this is true if X is either R τ or ω τ and a cardinal τ is infinite and not countably cofinal.

On nowhere first-countable compact spaces with countable π -weight

Jan van Mill (2015)

Commentationes Mathematicae Universitatis Carolinae

The minimum weight of a nowhere first-countable compact space of countable π -weight is shown to be κ B , the least cardinal κ for which the real line can be covered by κ many nowhere dense sets.

On open maps and related functions over the Salbany compactification

Mbekezeli Nxumalo (2024)

Archivum Mathematicum

Given a topological space X , let 𝒰 X and η X : X 𝒰 X denote, respectively, the Salbany compactification of X and the compactification map called the Salbany map of X . For every continuous function f : X Y , there is a continuous function 𝒰 f : 𝒰 X 𝒰 Y , called the Salbany lift of f , satisfying ( 𝒰 f ) η X = η Y f . If a continuous function f : X Y has a stably compact codomain Y , then there is a Salbany extension F : 𝒰 X Y of f , not necessarily unique, such that F η X = f . In this paper, we give a condition on a space such that its Salbany map is open. In particular,...

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