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Let $\cal{P}$ be an open filter base for a filter $\cal{F}$ on $X$. We denote by $C^{\cal{P}}(X)$ ($C_{\infty\cal{P}}(X)$) the set of all functions $f\in C(X)$ where $Z(f)$ ($\{x: |f(x)|< \frac{1}{n}\})$ contains an element of $\cal{P}$.…

General Topology · Mathematics 2014-01-20 A. Taherifar

Our aim is to study certain algebraic properties of the ring $C(X)_\mathcal{P}$ of real-valued functions on $X$ whose closure of discontinuity set is in an ideal of closed sets. We characterize $\mathcal{P}P$-spaces using $z$-ideals and…

General Topology · Mathematics 2024-02-05 Amrita Dey , Sagarmoy Bag , Dhananjoy Mandal

Let $\Sigma (X,\mathbb{C})$ denote the collection of all the rings between $C^*(X,\mathbb{C})$ and $C(X,\mathbb{C})$. We show that there is a natural correlation between the absolutely convex ideals/ prime ideals/maximal…

General Topology · Mathematics 2020-01-28 Amrita Acharyya , Sudip Kumar Acharyya , Sagarmoy Bag , Joshua Sack

Intermediate rings of real valued continuous functions with countable range on a Hausdorff zero-dimensional space $X$ are introduced in this article. Let $\Sigma_c(X)$ be the family of all such intermediate rings $A_c(X)$'s which lie…

General Topology · Mathematics 2019-12-05 Sudip Kumar Acharyya , Rakesh Bharati , A. Deb Ray

A topological space $X$ is called submaximal if every dense subset of $X$ is open. In this paper, we show that if $\beta X$, the Stone-\v{C}ech compactification of $X$, is a submaximal space, then $X$ is a compact space and hence $\beta…

General Topology · Mathematics 2022-05-17 Rostam Mohamadian

Let $X$ be a completely regular topological space. We assign to each (set theoretic) ideal of $X$ an (algebraic) ideal of $C_B(X)$, the normed algebra of continuous bounded complex valued mappings on $X$ equipped with the supremum norm. We…

Functional Analysis · Mathematics 2016-06-08 M. R. Koushesh

In this paper, we study some properties of the ring $C(X)_F$ of all real valued functions which are continuous except on some finite subsets of $X$. We show that $C(X)_F$ is closed under uniform limit if and only if the set of all…

General Topology · Mathematics 2021-09-15 Samir Ch Mandal , Sagarmoy Bag , Dhananjoy Mandal

This paper conglomerates our findings on the space $C(X)$ of all real valued continuous functions, under different generalizations of the topology of uniform convergence and the $m$-topology. The paper begins with answering all the…

General Topology · Mathematics 2024-11-01 Pratip Nandi , Rakesh Bharati , Atasi Deb Ray , Sudip Kumar Acharyya

Let $X$ be a zero-dimensional space and $C_c(X)$ be the set of all continuous real valued functions on $X$ with countable image. In this article we denote by $C_c^K(X)$ (resp., $C_{c}^{\psi}(X)$) the set of all functions in $C_c(X)$ with…

General Topology · Mathematics 2015-07-01 Alireza Olfati

For a nonempty topological space X, the ring of all real-valued functions on $X$ with pointwise addition and multiplication is denoted by $F(X)$ and continuous members of $F(X)$ is denoted by $C(X)$. Let $A(X)$ be a subring of $F(X)$ and…

General Topology · Mathematics 2021-07-06 Mohammad Reza Ahmadi Zand

Let $\mathcal{P}$ be an ideal of closed subsets of a topological space $X$. Consider the ring, $C(X)_\mathcal{P}$ of real valued functions on $X$ whose closure of discontinuity set is a member of $\mathcal{P}$. We investigate the ring…

General Topology · Mathematics 2023-04-18 Amrita Dey , Sudip Kumar Acharyya , Sagarmoy Bag , Dhananjoy Mandal

For a Hausdorff zero-dimensional topological space $X$ and a totally ordered field $F$ with interval topology, let $C_c(X,F)$ be the ring of all $F-$valued continuous functions on $X$ with countable range. It is proved that if $F$ is either…

General Topology · Mathematics 2021-11-24 Sudip Kumar Acharyya , Atasi Deb Ray , Pratip Nandi

For a Tychonoff space $X$, let $C_k(X)$ and $C_p(X)$ be the spaces of real-valued continuous functions $C(X)$ on $X$ endowed with the compact-open topology and the pointwise topology, respectively. If $X$ is compact, the classic result of…

Functional Analysis · Mathematics 2018-09-25 Saak Gabriyelyan , Jerzy Kcakol

Let $P$ be a directed set and $X$ a space. A collection $\mathcal{C}$ of subsets of $X$ is \emph{$P$-locally finite} if $\mathcal{C}=\bigcup \{ \mathcal{C}_p : p \in P\}$ where (i) if $p \le p'$ then $\mathcal{C}_p \subseteq…

General Topology · Mathematics 2015-01-09 Ziqin Feng , Paul Gartside , Jeremiah Morgan

For any Tychonoff space $X$ let $C_p(X)$ (resp., $C^*_p(X)$) be the set of all continuous (resp., and bounded) functions on $X$ with the pointwise convergence topology. Given Tychonoff spaces $X$ and $Y$, Uspenskij \cite{us} proved that if…

General Topology · Mathematics 2026-05-05 Vesko Valov

We expand \v{C}ech cohomology of a topological space $X$ with values in a presheaf on $X$ to \v{C}ech cohomology of a commutative ring with unity $R$ with values in a presheaf on $R$. The strategy is to observe that both the set of open…

Category Theory · Mathematics 2024-09-17 Ana Luiza Tenório , Peter Arndt , Hugo Luiz Mariano

We solve the last standing open problem from the seminal paper by J. Gerlits and Zs. Nagy, which was later reposed by A. Miller, T. Orenshtein and B. Tsaban. Namely, we show that under p = c there is a \delta-set that is not a \gamma-set.…

General Topology · Mathematics 2023-05-15 Serhii Bardyla , Jaroslav Supina , Lyubomyr Zdomskyy

In the set of continuous functions C(X,Y) where Y has a topology close to being discrete, there is an equivalence relation on X which characterizes the quasi-components of X. If Y satisfies weak algebraic conditions with a single binary…

Rings and Algebras · Mathematics 2014-07-14 Harvey J. Charlton

In this article we introduce the zero-divisor graphs $\Gamma_\mathscr{P}(X)$ and $\Gamma^\mathscr{P}_\infty(X)$ of the two rings $C_\mathscr{P}(X)$ and $C^\mathscr{P}_\infty(X)$; here $\mathscr{P}$ is an ideal of closed sets in $X$ and…

Commutative Algebra · Mathematics 2023-06-27 Sudip Kumar Acharyya , Atasi Deb Ray , Pratip Nandi

The set of all maximal ideals of the ring $\mathcal{M}(X,\mathcal{A})$ of real valued measurable functions on a measurable space $(X,\mathcal{A})$ equipped with the hull-kernel topology is shown to be homeomorphic to the set $\hat{X}$ of…

Functional Analysis · Mathematics 2018-06-11 Sudip Kumar Acharyya , Sagarmoy Bag , Joshua Sack
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