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Using approximation by continuous functions we prove the following statements to types of tightness in a space $Q_p(X, \mathbb{R})$ of all quasicontinuous real-valued functions with the topology $\tau_p$ of pointwise convergence: the…

General Topology · Mathematics 2025-03-06 Anton E. Lipin , Alexander V. Osipov

In this paper, we introduce and explore a new class of topological spaces termed as SC*-normal spaces, defined via SC*-open sets. The concept of SC*-normality is analyzed in relation to classical notions such as normal spaces and g-normal…

General Topology · Mathematics 2025-05-13 Neeraj Kumar Tomar , Fahed Zulfeqarr , M. C. Sharma

For a Tychonoff space $X$ and a family $\lambda$ of subsets of $X$, we denote by $C_{\lambda}(X)$ the space of all real-valued continuous functions on $X$ with the set-open topology. In this paper, we study the Menger and projective Menger…

General Topology · Mathematics 2018-03-28 Alexander V. Osipov

We prove that for any topological space $X$ of countable tightness, each \sigma-convex subspace $\F$ of the space $SC_p(X)$ of scatteredly continuous real-valued functions on $X$ has network weight $nw(\F)\le nw(X)$. This implies that for a…

General Topology · Mathematics 2013-06-04 Taras Banakh , Bogdan Bokalo , Nadiya Kolos

We define the concept of continuum wise expansive for set-valued functions and prove that if a compact metric space admit a set-valued $cw$-expansive function then the topological entropy of $X$ is positive.} We also introduce the notion of…

Dynamical Systems · Mathematics 2015-10-27 Welington Cordeiro , Maria José Pacífico

We construct a variety of mappings of the unit interval into $\mathcal{L}^p([0,1])$ to generalize classical examples of $\mathcal{L}^p$-convergence of sequences of functions with simultaneous pointwise divergence. By establishing relations…

Classical Analysis and ODEs · Mathematics 2012-07-17 Vaios Laschos , Christian Mönch

The famous Rosenthal-Lacey theorem asserts that for each infinite compact space $K$ the Banach space $C(K)$ admits a quotient which is either a copy of $c_{0}$ or $\ell_{2}$. The aim of the paper is to study a natural variant of this result…

Functional Analysis · Mathematics 2020-04-09 T. Banakh , J. Kąkol , W. Śliwa

There are presented certain results on extending continuous linear operators defined on spaces of E-valued continuous functions (defined on a compact Hausdorff space X) to linear operators defined on spaces of E-valued measurable functions…

Functional Analysis · Mathematics 2017-05-26 Piotr Niemiec

We call a function $f: X\to Y$ $P$-preserving if, for every subspace $A \subset X$ with property $P$, its image $f(A)$ also has property $P$. Of course, all continuous maps are both compactness- and connectedness-preserving and the natural…

General Topology · Mathematics 2018-01-22 I. Juhász , J. van Mill

We give a characterization of the $\Delta_1$-property of any Tychonoff space $X$ in terms of the function space $B_1(X)$ of all Baire-one real-valued functions on a space $X$ with the topology of pointwise convergence. We establish that for…

General Topology · Mathematics 2025-04-16 Alexander V. Osipov

We consider the space of functions almost in $L_p$ and endow it with the topology of asymptotic $L_p$-convergence. This yields a completely metrizable topological vector space which, on finite measure spaces, coincides with the space of…

Functional Analysis · Mathematics 2025-12-01 Nuno J. Alves

The aim of this paper is to study the Frechet-Urysohn property of the space $Q_p(X,\mathbb{R})$ of real-valued quasicontinuous functions, defined on a Hausdorff space $X$, endowed with the pointwise convergence topology. It is proved that…

General Topology · Mathematics 2023-02-15 Alexander V. Osipov

A space $X$ is projectively Hurewicz provided every separable metrizable continuous image of $X$ is Hurewicz. In this paper we prove that the projectively Hurewicz property is $t$-invariant, i.e., if $C_p(X)$ is homeomorphic to $C_p(Y)$ and…

General Topology · Mathematics 2023-06-06 Alexander V. Osipov

In this paper we continue to study the property of separability of functional space C(X) with the open-point and bi-point-open topologies.

General Topology · Mathematics 2016-04-18 Alexander V. Osipov

We study separating function sets. We find some necessary and sufficient conditions for $C_p(X)$ or $C_p^2(X)$ to have a point-separating subspace that is a metric space with certain nice properties. One of the corollaries to our discussion…

General Topology · Mathematics 2017-08-29 Raushan Buzyakova , Oleg Okunev

In this paper, we consider certain topological properties along with certain types of mappings on these spaces defined by the notion of ideal convergence. In order to do that, we primarily follow in the footsteps of the earlier studies of…

General Topology · Mathematics 2023-01-03 Pratulananda Das , Upasana Samanta , Shou Lin

In this paper, we give a topological version of Scott convergence theorem for locally hypercompact spaces. We introduce the notion of $\mathcal{S}^*_X$-convergence on a $T_0$ topological space $X$, and define the notion of finitely…

General Topology · Mathematics 2023-08-09 Yuxu Chen , Hui Kou

We present new results regarding calibers in the function spaces $C_p(X)$. Our main theorem is that $C_p(X)$ is strongly \v{S}anin whenever $X$ is a submetrizable space; this improves an earlier result due to Tkachuk: $C_p(X)$ is \v{S}anin…

General Topology · Mathematics 2024-08-09 Alejandro Ríos-Herrejón , Ángel Tamariz-Mascarúa

Let $X$ be a topological space. A subset of $C(X)$, the space of continuous real-valued functions on $X$, is a partially ordered set in the pointwise order. Suppose that $X$ and $Y$ are topological spaces, and $A(X)$ and $A(Y)$ are subsets…

Functional Analysis · Mathematics 2014-08-22 Denny H. Leung , Wee-Kee Tang

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