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We show that for a given initial point the typical, in the sense of Baire category, nonexpansive compact valued mapping $F$ has the following properties: there is a unique sequence of successive approximations and this sequence converges to…

Functional Analysis · Mathematics 2023-08-14 Emir Medjic

We show that if a rearrangement invariant Banach function space $E$ on the positive semi-axis satisfies a non-trivial lower $q-$ estimate with constant $1$ then the corresponding space $E(\nm)$ of $\tau-$measurable operators, affiliated…

Functional Analysis · Mathematics 2016-09-06 Peter G. Dodds , T. K. Dodds , Paddy N. Dowling , Christopher J. Lennard , Fyodor A. Sukochev

We introduce the set-self-Tietze property, an analogue of the self-Tietze property for upper semi-continuous set-valued functions. A topological space $X$ is self-Tietze, if for every closed $A \subseteq X$ and continuous function $f \colon…

General Topology · Mathematics 2026-03-17 Andrew Wood

A topological space $X$ has the strong Pytkeev property at a point $x\in X$ if there exists a countable family $\mathcal N$ of subsets of $X$ such that for each neighborhood $O_x\subset X$ and subset $A\subset X$ accumulating at $x$, there…

General Topology · Mathematics 2021-11-01 Taras Banakh , Arkady Leiderman

In this paper we present a few properties of $K$-partitions, which are partitions of Baire spaces such that all subfamilies of such a partition sum to a set with the Baire property. Among the result proven we have general existence result…

Logic · Mathematics 2022-05-26 Sławomir Kusiński

Assume that $X$ is a regular space. We study topological properties of the family $S_c(X)$ of nontrivial convergent sequences in $X$ equipped with the Vietoris topology. We show that if $X$ has no isolated points, then $S_c(X)$ is a space…

General Topology · Mathematics 2018-01-18 Michał Popławski

We introduce and study adhesive spaces. Using this concept we obtain a characterization of stable Baire maps $f:X\to Y$ of the class $\alpha$ for wide classes of topological spaces. In particular, we prove that for a topological space $X$…

General Topology · Mathematics 2016-06-02 Olena Karlova , Volodymyr Mykhaylyuk

We consider certain strengthenings of property (T) relative to Banach spaces that are satisfied by high rank Lie groups. Let X be a Banach space for which, for all k, the Banach--Mazur distance to a Hilbert space of all k-dimensional…

Functional Analysis · Mathematics 2017-06-28 Tim de Laat , Masato Mimura , Mikael de la Salle

Let $X$ be a topological space. Let $X_0 \subseteq X$ be a second countable subspace. Also, assume that $X$ is first countable at any point of $X_0$. Then we provide some conditions under which we ensure that $X_0$ is not Baire.

General Topology · Mathematics 2014-03-07 Mehdi Pourbarat , Neda Abbasi

Under $\text{CH}$ we construct a partition of Baire space into compact sets, which is indestructible by countably supported iteration and product of Sacks forcing of any length, answering a question of Newelski. Further, we present an…

Logic · Mathematics 2025-05-08 Vera Fischer , Lukas Schembecker

We prove a uniformly continuous linear extension principle in topological vector spaces from which we derive a very short and canonical construction of the Lebesgue integral of Banach space valued maps on a finite measure space. The Vitali…

Functional Analysis · Mathematics 2013-05-08 Ben Berckmoes

In this article, we continue our study of Baire one functions on a topological space $X$, denoted by $B_1(X)$ and extend the well known M. H. Stones's theorem from $C(X)$ to $B_1(X)$. Introducing the structure space of $B_1(X)$, it is…

General Topology · Mathematics 2022-01-10 A. Deb Ray , Atanu Mondal

We prove the following results. 1. If $X$ is a $\alpha$-favourable space, $Y$ is a regular space, in which every separable closed set is compact, and $f:X\times Y\to\mathbb R$ is a separately continuous everywhere jointly discontinuous…

General Topology · Mathematics 2016-01-14 V. V. Mykhaylyuk

Let $O$ be the ring of power series in one variable over a finite field, with $K$ its fraction field. We introduce the notion of a "formal $K$-vector space"; this is a certain kind of $K$-vector space object in the category of formal…

Number Theory · Mathematics 2013-04-04 Jared Weinstein

We study the uniform computational content of different versions of the Baire Category Theorem in the Weihrauch lattice. The Baire Category Theorem can be seen as a pigeonhole principle that states that a complete (i.e., "large") metric…

Logic · Mathematics 2018-11-14 Vasco Brattka , Matthew Hendtlass , Alexander P. Kreuzer

The Kestelman-Borwein-Ditor Theorem asserts that a non-negligible subset of $\mathbb{R}$ which is Baire (=has the Baire property, BP) or measurable is shift-compact: it contains some subsequence of any null sequence to within translation by…

Classical Analysis and ODEs · Mathematics 2019-01-29 H. I. Miller , L. Miller-Van Wieren , A. J. Ostaszewski

We say that binary relation E on a space X is a clopen graph on X iff E is symmetric and irreflexive and clopen relative to X x X minus its diagonal. Equivalently for distinct x, y in X there are open sets U,V with (x,y) in U x V and either…

Logic · Mathematics 2012-11-01 Arnold W. Miller

Let X be a separable metric space and let \beta be the strict topology on the space of bounded continuous functions on X, which has the space of \tau-additive Borel measures as a continuous dual space. We prove a Banach-Dieudonne\'{e} type…

Functional Analysis · Mathematics 2016-09-06 Richard Kraaij

We prove a variation norm Carleson theorem for Walsh-Fourier series of functions with values in a UMD Banach space. Our only hypothesis on the Banach space is that it has finite tile-type, a notion introduced by Hyt\"onen and Lacey. Given q…

Classical Analysis and ODEs · Mathematics 2019-05-28 Tuomas P. Hytönen , Michael T. Lacey , Ioannis Parissis

Recall that a Hausdorff space $X$ is said to be Namioka if for every compact (Hausdorff) space $Y$ and every metric space $Z$, every separately continuous function $f:X\times{Y}\rightarrow{Z}$ is continuous on $D\times{Y}$ for some dense…

General Topology · Mathematics 2012-07-17 Zbigniew Piotrowski , Russell Waller