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In this paper we introduce and study so-called $k^*$-metrizable spaces forming a new class of generalized metric spaces, and display various applications of such spaces in topological algebra, functional analysis, and measure theory. By…

General Topology · Mathematics 2011-10-11 T. O. Banakh , V. I. Bogachev , A. V. Kolesnikov

The Haagerup approximation property (HAP) is defined for finite von Neumann algebras in such a way that the group von Neumann algebra of a discrete group has the HAP if and only if the group itself has the Haagerup property. The HAP has…

Operator Algebras · Mathematics 2015-02-11 Rui Okayasu , Narutaka Ozawa , Reiji Tomatsu

We prove the almost sure weak convergence of a stochastic proximal point method for minimizing a convex integral function in the general nonlinear context of complete geodesic metric spaces of nonpositive curvature (so-called Hadamard…

Optimization and Control · Mathematics 2026-05-21 Nicholas Pischke

For a Banach space $B$ and for a class $\A$ of its bounded closed retracts, endowed with the Hausdorff metric, we prove that retractions on elements $A \in \A$ can be chosen to depend continuously on $A$, whenever nonconvexity of each $A…

General Topology · Mathematics 2010-04-14 Dušan Repovš , Pavel V. Semenov

Necessary and sufficient conditions for the exponentiation of finite-dimensional real Lie algebras of linear operators on complete Hausdorff locally convex spaces are obtained, focused on the equicontinuous case - in particular, necessary…

Functional Analysis · Mathematics 2019-11-12 Rodrigo A. H. M. Cabral

Given a compact metric space X and a unital C*-algebra A, we introduce a family of seminorms on the C*-algebra of continuous functions from X to A, denoted C(X, A), induced by classical Lipschitz seminorms that produce compact quantum…

Operator Algebras · Mathematics 2018-03-28 Konrad Aguilar , Tristan Bice

The aim of this paper is to introduce the concepts of homotopical smallness and closeness. These are the properties of homotopical classes of maps that are related to recent developments in homotopy theory and to the construction of…

Geometric Topology · Mathematics 2011-01-05 Ziga Virk

We prove that the C*-algebra of a minimal diffeomorphism satisfies Blackadar's Fundamental Comparability Property for positive elements. This leads to the classification, in terms of K-theory and traces, of the isomorphism classes of…

Operator Algebras · Mathematics 2015-05-13 Andrew S. Toms

We initiate the rigorous study of classification in quasi-metric spaces. These are point sets endowed with a distance function that is non-negative and also satisfies the triangle inequality, but is asymmetric. We develop and refine a…

Machine Learning · Computer Science 2019-09-24 Lee-Ad Gottlieb , Shira Ozeri

This paper uses a net-theoretic approach to convergence spaces, aimed to simplify the description of continuous convergence in order to apply it in problems concerning Homotopy Theory. We present methods for handling homotopies of limit…

Algebraic Topology · Mathematics 2024-10-30 Renan Maneli Mezabarba , Rodrigo Santos Monteiro , Thales Fernando Vilamaior Paiva

We introduce three metrics on the set of quantum probability measures over a compact Hausdorff space and characterize them in terms of the completely bounded norm of the corresponding unital completely positive maps. We extend the existing…

Operator Algebras · Mathematics 2024-09-26 Georgios Baziotis

Given a weight vector $\tau=(\tau_{1}, \dots, \tau_{n}) \in \mathbb{R}^{n}_{+}$ with each $\tau_{i}$ bounded by certain constraints, we obtain a lower bound for the Hausdorff dimension of the set of $\tau$-approximable points points over a…

Number Theory · Mathematics 2020-10-13 Victor Beresnevich , Jason Levesley , Benjamin Ward

This note provides a correct proof of the result claimed by the second author that locally compact normal spaces are collectionwise Hausdorff in certain models obtained by forcing with a coherent Souslin tree. A novel feature of the proof…

General Topology · Mathematics 2019-08-15 Alan Dow , Franklin D. Tall

We investigate the approximation of Monge--Kantorovich problems on general compact metric spaces, showing that optimal values, plans and maps can be effectively approximated via a fully discrete method. First we approximate optimal values…

Numerical Analysis · Mathematics 2024-01-29 Maximiliano Frungillo

If $(X,d)$ is a metric space then the map $f\colon X\to X$ is defined to be a weak contraction if $d(f(x),f(y))<d(x,y)$ for all $x,y\in X$, $x\neq y$. We determine the simplest non-closed sets $X\subseteq \mathbb{R}^n$ in the sense of…

Classical Analysis and ODEs · Mathematics 2014-10-01 Richárd Balka

Let $X$ be a paracompact space, let $G$ be a finite group acting freely on $X$ and let $H$ a cyclic subgroup of $G$ of prime order $p$. Let $f:X\rightarrow M$ be a continuous map where $M$ is a connected $m$-manifold (orientable if $p>2$)…

Algebraic Topology · Mathematics 2016-11-01 Denise de Mattos , Edivaldo L. dos Santos , Taciana O. Souza

We examine the selective screenability property in topological groups. In the metrizable case we also give characterizations in terms of the Haver property and finitary Haver property respectively relative to left-invariant metrics. We…

General Topology · Mathematics 2008-01-09 Liljana Babinkostova

We show a Wolff-Denjoy type theorem in the case of a one-parameter continuous semigroups of nonexpansive mappings in which there is a compact mapping. Using the notion of attractor we are also able to prove some specific properties directly…

Functional Analysis · Mathematics 2024-01-29 Aleksandra Huczek

We prove that the countable intersection of $C^1$-diffeomorphic images of certain Diophantine sets has full Hausdorff dimension. For example, we show this for the set of badly approximable vectors in $\mathbb{R}^d$, improving earlier…

Number Theory · Mathematics 2015-05-28 Ryan Broderick , Lior Fishman , Dmitry Kleinbock , Asaf Reich , Barak Weiss

We generalize the Arzel\`a-Ascoli theorem in the space of continuous maps on a compact interval with values in Euclidean N-space by providing a quantitative link between the Hausdorff measure of noncompactness in this space and a natural…

Functional Analysis · Mathematics 2013-03-15 Ben Berckmoes