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For an index set $\Gamma$ and a cardinal number $\kappa$ the $\Sigma_{\kappa}$-product of real lines $\Sigma_{\kappa}(\mathbb{R}^{\Gamma})$ consist of all elements of $\mathbb{R}^{\Gamma}$ with $<\kappa$ nonzero coordinates. A compact space…

一般拓扑 · 数学 2024-07-08 Krzysztof Zakrzewski

We consider two natural topologies on the space $S(X\times Y,Z)$ of all separately continuous functions defined on the product of two topological spaces $X$ and $Y$ and ranged into a topological or metric space $X$. These topologies are the…

一般拓扑 · 数学 2025-01-03 Oleksandr Maslyuchenko , Vadym Myronyk , Roman Ivasiuk

For any cardinal number $\kappa$ and an index set $\Gamma$, $\Sigma_\kappa$-product of real lines consists of elements of ${\mathbb R}^\Gamma$ having $<\kappa$ nonzero coordinates. A compact space $K$ is $\kappa$-Corson compact if it can be…

一般拓扑 · 数学 2023-07-10 Witold Marciszewski , Grzegorz Plebanek , Krzysztof Zakrzewski

We prove that if K is a remainder of the Hilbert space (i.e., K is the complement of the Hilbert space in its metrizable compactification) then every non-one-point closed image of K either contains a compact set with no transfinite…

一般拓扑 · 数学 2017-12-21 Elżbieta Pol , Roman Pol

Supplementing and expanding classical results, for compact spaces $K$ and $L$, $L$ metric, and their Banach spaces $\mathcal{C}(L)$ and $\mathcal{C}(K)$ of continuous real-valued functions, we provide several characterizations of the…

泛函分析 · 数学 2024-11-28 Jakub Rondoš , Damian Sobota

Some new classes of compacta $K$ are considered for which $C(K)$ endowed with the pointwise topology has a countable cover by sets of small local norm--diameter.

泛函分析 · 数学 2015-10-20 Wiesław Kubiś , Aníbal Moltó , Stanimir Troyanski

Given a compact Polish space $E$ and the hyperspace of its compact subsets $\mathcal{K}(E)$, we consider the class of $G_{\delta}$ $\sigma$-ideals of compact subsets of $E$ that can be represented via a compact subset of $\mathcal{K}(E)$.…

逻辑 · 数学 2019-02-26 Maya Saran

Let $\mathcal K$ be a complete quasivariety of completely regular universal topological algebras of continuous signature $\mathcal E$ (which means that $\mathcal K$ is closed under taking subalgebras, Cartesian products, and includes all…

一般拓扑 · 数学 2012-02-22 T. Banakh , O. Hryniv

We show that an embedding of a fixed 0-dimensional compact space $K$ into the \v{C}ech--Stone remainder $\omega^*$ as a nowhere dense P-set is the unique generic limit, a special object in the category consisting of all continuous maps from…

一般拓扑 · 数学 2024-07-09 Wiesław Kubiś , Andrzej Kucharski , Sławomir Turek

Assuming that there is a stationary set in $\omega_{2}$ of ordinals of countable cofinality that does not reflect, we prove that there exists a compact space which is not Corson compact and whose all continuous images of weight at most…

一般拓扑 · 数学 2016-08-09 Menachem Magidor , Grzegorz Plebanek

In this article we introduce a new class of weighted sequence spaces of Sobolev type and prove several compact embedding theorems for them. It is our contention that the chosen class is general enough so as to allow applications in various…

泛函分析 · 数学 2025-03-27 Pierre-A. Vuillermot

We prove that if continuum is not a Kunen cardinal, then there is a uniform Eberlein compact space $K$ such that the Banach space $C(K)$ does not embed isometrically into $\ell_\infty/c_0$. We prove a similar result for isomorphic…

泛函分析 · 数学 2018-12-12 Mikolaj Krupski , Witold Marciszewski

Let $\mathbf{TB}$ be the category of totally bounded, locally compact metric spaces with the $C_0$ coarse structures. We show that if $X$ and $Y$ are in $\mathbf{TB}$ then $X$ and $Y$ are coarsely equivalent if and only if their Higson…

一般拓扑 · 数学 2019-08-15 Kotaro Mine , Atsushi Yamashita

In his PhD Thesis Konstantinos Beros proved a number of results about compactly generated subgroups of Polish groups. Such a group is K-sigma - the countable union of compact sets. He notes that the group of rationals under addition with…

逻辑 · 数学 2013-05-23 Arnold W. Miller

Let $X$ be a locally compact topological space, $(Y,d)$ be a boundedly compact metric space and $LB(X,Y)$ be the space of all locally bounded functions from $X$ to $Y$. We characterize compact sets in $LB(X,Y)$ equipped with the topology of…

一般拓扑 · 数学 2018-03-29 Ľubica Holá , Dušan Holý

For locally compact groups, we define an analogue to Yu's property A that he defined for discrete metric spaces. We show that our property A for locally compact groups agrees with Roe's notion of property A for proper metric spaces, defined…

算子代数 · 数学 2013-10-22 Steven Deprez , Kang Li

We consider special subclasses of the class of Lindel\"of Sigma-spaces obtained by imposing restrictions on the weight of the elements of compact covers that admit countable networks: A space $X$ is in the class $L\Sigma(\leq\kappa)$ if it…

一般拓扑 · 数学 2012-10-23 Wieslaw Kubis , Oleg Okunev , Paul J. Szeptycki

Extending a result of R. de la Vega, we prove that an infinite homogeneous compactum has cardinality $\mathfrak{c}$ if either it is the union of countably many dense or finitely many arbitrary countably tight subspaces. The question if…

一般拓扑 · 数学 2016-07-05 István Juhász , Jan van Mill

We prove that the countable product of supercomplete spaces having a countable closed cover consisting of partition-complete subspaces is supercomplete with respect to its metric-fine coreflection. Thus, countable products of…

一般拓扑 · 数学 2007-05-23 Aarno Hohti , Miroslav Husek , Jan Pelant

We show that, under suitably general formulations, covering properties, accumulation properties and filter convergence are all equivalent notions. This general correspondence is exemplified in the study of products. Let $X$ be a product of…

一般拓扑 · 数学 2023-03-28 Paolo Lipparini
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