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Related papers: Selectors for dense subsets of function spaces

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For a Tychonoff space $X$, we denote by $(C(X), \tau_k, \tau_p)$ the bitopological space of all real-valued continuous functions on $X$ where $\tau_k$ is the compact-open topology and $\tau_p$ is the topology of pointwise convergence. In…

General Topology · Mathematics 2019-03-21 Daniil Lyakhovets , Alexander V. Osipov

In paper we study relationships between covering properties of a topological space $X$ and the space $(USC^*(X),\tau_{\mathcal{B}})$ of bounded upper semicontinuous functions on $X$ with the topology $\tau_{\mathcal{B}}$ defined by the…

General Topology · Mathematics 2022-04-19 Lev Bukovský , Alexander V. Osipov

For a Tychonoff space $X$, we will denote by $USC_{p}(X)$ ($B_1(X)$) a set of all real-valued upper semicontinuous functions (a set of all Baire functions of class 1) defined on $X$ endowed with the pointwise convergence topology. In this…

General Topology · Mathematics 2018-09-27 Alexander V. Osipov , Evgenii G. Pytkeev

We give a characterization of countable discrete subspace $A$ of a topological space $X$ such that there exists a (linear) continuous mapping $\varphi:C_p^*(A)\to C_p(X)$ with $\varphi(y)|_A=y$ for every $y\in C_p^*(A)$. Using this…

General Topology · Mathematics 2016-04-22 V. Mykhaylyuk

A topological space is $Suslin$ ($Lusin$) if it is a continuous (and bijective) image of a Polish space. For a Tychonoff space $X$ let $C_p(X)$, $C_k(X)$ and $C_{{\downarrow}F}(X)$ be the space of continuous real-valued functions on $X$,…

General Topology · Mathematics 2021-11-01 Taras Banakh , Leijie Wang

We study the complexity of the space $C^*_p(X)$ of bounded continuous functions with the topology of pointwise convergence. We are allowed to use descriptive set theoretical methods, since for a separable metrizable space $X$, the…

Functional Analysis · Mathematics 2015-10-08 Martin Doležal , Benjamin Vejnar

Given a topological space $X$, we study the structure of $\infty$-convex subsets in the space $SC_p(X)$ of scatteredly continuous functions on $X$. Our main result says that for a topological space $X$ with countable strong fan tightness,…

General Topology · Mathematics 2014-12-04 Taras Banakh , Bogdan Bokalo , Nadiya Kolos

For a Tychonoff space X, we denote by B(X) the space of all Baire functions on X with the topology of pointwise convergence. In this paper we investigate selectors for sequences of countable dense and countable sequentially dense sets of…

General Topology · Mathematics 2017-11-08 Alexander V. Osipov

For a topological space X, let (RX)s := (RX,Ts) be the cartesian product of |X| copies of the real line R with the topology of the uniform convergence on separable subsets of X. In this article we analyze the subspace C(X) of (RX)s of all…

Generalizations of the theorems of Eberlein and Grothendieck on the precompactness of subsets of function spaces are considered: if $X$ is a countably compact space and $C_p(X)$ is a space of continuous functions in the pointwise topology…

General Topology · Mathematics 2024-11-06 E. A. Reznichenko

For a Tychonoff space $X$, we denote by $C_k(X)$ the space of all real-valued continuous functions on X with the compact-open topology. In this paper, we have gave characterization for $C_k(X)$ to satisfy $S_{fin}(S, S)$.

General Topology · Mathematics 2018-05-16 Alexander V. Osipov

We give the characteristics of selectors for sequences of dense sets of Cp(X) through the selection principles of a Tychonoff space X.

General Topology · Mathematics 2017-11-08 Alexander V. Osipov

The famous Michael selection theorem deals with the characterisation of paracompact spaces by continuous selections of lower semi-continuous mappings in Banach spaces. In this paper, we will discuss several equivalent forms of this theorem,…

Functional Analysis · Mathematics 2026-02-26 Valentin Gutev

In 1934, Whitney raised the question of how to recognize whether a function f defined on a closed subset X of Euclidean space is the restriction of a function that is continuously differentiable to order p. A necessary and sufficient…

Algebraic Geometry · Mathematics 2007-05-23 E. Bierstone , P. D. Milman , W. Pawlucki

Fix a d-minimal expansion of an ordered field. We consider the space $\mathcal D^p(M)$ of definable $\mathcal C^p$ functions defined on a definable $\mathcal C^p$ submanifold $M$ equipped with definable $\mathcal C^p$ topology. The set of…

Logic · Mathematics 2025-02-04 Masato Fujita

We study properties of strongly separately continuous mappings defined on subsets of products of topological spaces equipped with the topology of pointwise convergence. In particular, we give a necessary and sufficient condition for a…

General Topology · Mathematics 2014-11-26 Olena Karlova , Volodymyr Mykhaylyuk

This paper addresses the Asplund property for the space of continuous functions $C_k(X)$ equipped with the compact-open topology, when $X$ is an arbitrary Tychonoff space. Motivated by inconsistent definitions in prior literature extending…

Functional Analysis · Mathematics 2025-10-03 Marian Fabian , Jerzy Kcakol , Arkady Leiderman

The concept of Hausdorff continuous interval valued functions, developed within the theory of Hausdorff approximations and originaly defined for interval valued functions of one real variable is extended to interval valued functions defined…

Analysis of PDEs · Mathematics 2007-05-23 Roumen Anguelov

For a Hausdorff space $X$ we denote be $2^X$ the family of all closed subsets of $X$. In this paper we continue to research relationships between closure -type properties of hyperspaces over a space $X$ and covering properties of $X$. We…

General Topology · Mathematics 2018-11-05 Alexander V. Osipov

A topological space $X$ is Baire if the Baire Category Theorem holds for $X$, i.e., the intersection of any sequence of open dense subsets of $X$ is dense in $X$. One of the interesting problems in the theory of functional spaces is the…

General Topology · Mathematics 2024-09-05 Alexander V. Osipov
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