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Let $X$ be a paracompact topological space and $Y$ be a Banach space. In this paper, we will characterize the Baire-1 functions $f:X\rightarrow{Y}$ by their graph: namely, we will show that $f$ is a Baire-1 function if and only if its graph…

Classical Analysis and ODEs · Mathematics 2026-05-20 Balázs Maga

We investigate Baire-one functions whose graph is contained in a graph of usco mapping. We prove in particular that such a function defined on a metric space with values in $\mathbb{R}^d$ is the pointwise limit of a sequence of continuous…

General Topology · Mathematics 2009-05-21 Ondřej F. K. Kalenda

We consider a real-valued function $f$ defined on the set of infinite branches $X$ of a countably branching pruned tree $T$. The function $f$ is said to be a \textit{limsup function} if there is a function $u \colon T \to \mathbb{R}$ such…

General Topology · Mathematics 2020-10-08 Márton Elekes , János Flesch , Viktor Kiss , Donát Nagy , Márk Poór , Arkadi Predtetchinski

Let $K$ be a compact metric space. A real-valued function on $K$ is said to be of Baire class one (Baire-1) if it is the pointwise limit of a sequence of continuous functions. In this paper, we study two well known ordinal indices of…

Classical Analysis and ODEs · Mathematics 2007-05-23 Denny H. Leung , Wee-Kee Tang

We give a new characterization of the Baire class 1 functions (defined on an ultrametric space) by proving that they are exactly the pointwise limits of sequences of full functions (which are particularly simple Lipschitz functions).…

Logic · Mathematics 2010-03-25 L. Motto Ros

A function f:R -> R is approximately continuous iff it is continuous in the density topology, i.e., for any ordinary open set U the set E=f^{-1}(U) is measurable and has Lebesgue density one at each of its points. Denjoy proved that…

Logic · Mathematics 2016-09-06 M. Laczkovich , Arnold W. Miller

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 $X$. In this paper, we have obtained that the space $B^{st}_1(X)$ of pointwise…

General Topology · Mathematics 2022-06-06 Alexander V. Osipov

Examples of discontinuous functions already appear in the work of Euler, Abel, Dirichlet, Fourier, and Bolzano. A ground-breaking discovery due to Baire was that many discontinuous functions are well-behaved in that they are the pointwise…

Logic · Mathematics 2026-02-06 Dag Normann , Sam Sanders

A topological space $X$ is Baire if the intersection of any sequence of open dense subsets of $X$ is dense in $X$. One of the interesting problems for the space of Baire functions is the Banakh-Gabriyelyan problem: Let $\alpha$ be a…

General Topology · Mathematics 2025-03-06 Alexander V. Osipov

A topological space $X$ is Baire if the intersection of any sequence of open dense subsets of $X$ is dense in $X$. Let $C_p(X,[0,1])$ denote the space of all continuous $[0,1]$-valued functions on a Tychonoff space $X$ with the topology of…

General Topology · Mathematics 2022-03-14 Alexander V. Osipov , Evgenii G. Pytkeev

We compare possibilities of extension of bounded and unbounded Baire-one functions from subspaces of topological spaces.

General Topology · Mathematics 2018-10-30 Olena Karlova , Volodymyr Mykhaylyuk

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

Recently some Mathematician extend the notion of Baire one functions. We give some nice relations between this subring and some nice functions rings on a topological spaces.

General Topology · Mathematics 2021-06-08 Mohammad Reza Ahmadi Zand , Zahra Khosravi

In this paper, we focus on the existence of accumulation points of the subset defined by the real projection of the zeros of the partial sums of the Riemann zeta functions. That would imply the existence of an infinite amount of zeros of…

Complex Variables · Mathematics 2011-02-15 Eric Dubon , Gaspar Mora , Juan Matías Sepulcre , Jose Ignacio Úbeda , Tomas Vidal

We consider the set of Baire 1 functions endowed with the pointwise partial ordering and investigate the structure of the linearly ordered subsets.

Classical Analysis and ODEs · Mathematics 2011-09-27 Márton Elekes

It is solved the problem on constructed of separately continuous functions on product of two topological spaces with given restriction. In particular, it is shown that for every topological space $X$ and first Baire class function $g:X\to…

General Topology · Mathematics 2016-02-01 V. V. Mykhaylyuk

We study the Fourier dimensions of graphs of real-valued functions defined on the unit interval [0,1]. Our results imply that the graph of the fractional Brownian motion is almost surely not a Salem set, answering in part a question of…

Classical Analysis and ODEs · Mathematics 2014-10-06 Jonathan M. Fraser , Tuomas Orponen , Tuomas Sahlsten

Indicator functions mentioned in the title are constructed on an arbitrary nondiscrete locally compact Abelian group of finite dimension. Moreover, they can be obtained by small perturbation from any indicator function fixed beforehand. In…

Classical Analysis and ODEs · Mathematics 2020-06-05 S. V. Kislyakov , P. S. Perstneva

Let $\mathcal{C}$ be a family of edge-colored graphs. A $t$-edge colored graph $G$ is $(\mathcal{C}, t)$-saturated if $G$ does not contain any graph in $\mathcal{C}$ but the addition of any edge in any color in $[t]$ creates a copy of some…

Given a finite number of samples of a continuous set-valued function F, mapping an interval to non-empty compact subsets of $\mathbb{R}^d$, $F: [a,b] \to K(\mathbb{R}^d)$, we discuss the problem of computing good approximations of F. We…

Numerical Analysis · Mathematics 2025-01-27 Nira Dyn , David Levin
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