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We give a complete characterization of the locally compact groups that are non-elementary Gromov-hyperbolic and amenable. They coincide with the class of mapping tori of discrete or continuous one-parameter groups of compacting…

Group Theory · Mathematics 2015-10-29 Pierre-Emmanuel Caprace , Yves de Cornulier , Nicolas Monod , Romain Tessera

We further investigate the weak topology generated by the irreducible unitary representations of a group $G$. A deep result due to Ernest \cite{Ernest1971} and Hughes \cite{Hughes1973} asserts that every weakly compact subset of a locally…

General Topology · Mathematics 2021-03-25 María V. Ferrer , Salvador Hernández

It is well known that strongly minimal groups are commutative. Whether this is true for various generalisations of strong minimality has been asked in several different settings (see Hyttinen [2002], Maesono [2007], Pillay and Tanovi\'c…

Logic · Mathematics 2017-04-14 Levon Haykazyan

We discuss the finiteness of the topological entropy of continuous endomorphims for some classes of locally compact groups. Firstly, we focus on the abelian case, imposing the condition of being compactly generated, and note an interesting…

Group Theory · Mathematics 2024-03-01 Francesco G. Russo , Olwethu Waka

A metric space $(M, d)$ is said to be universal for a class of metric spaces if all metric spaces in the class can be isometrically embedded into $(M, d)$. In this paper, for a metrizable space $Z$ possessing abundant subspaces, we first…

Metric Geometry · Mathematics 2024-09-27 Yoshito Ishiki , Katsuhisa Koshino

In this paper we show that for every congruent monotileable amenable group $G$ and for every metrizable Choquet simplex $K$, there exists a minimal $G$-subshift, which is free on a full measure set, whose set of invariant probability…

Dynamical Systems · Mathematics 2017-09-26 Paulina Cecchi , María Isabel Cortez

We perform a general study of the structure of locally compact modules over compactly generated abelian groups. We obtain a devissage result for such modules of the form "compact-by-sheer-by-discrete", and then study more specifically the…

Group Theory · Mathematics 2025-08-28 Yves Cornulier

The main result of this article is: THEOREM. Every homogeneous locally conical connected separable metric space that is not a $1$-manifold is strongly $n$-homogeneous for each $n \geq 2$ and countable dense homogeneous. Furthermore,…

General Topology · Mathematics 2017-06-02 Fredric D. Ancel , David P. Bellamy

We prove that the free locally convex space $L(X)$ over a metrizable space $X$ has countable tightness if and only if $X$ is separable.

General Topology · Mathematics 2014-07-08 S. S. Gabriyelyan

In 1985 S.~Saeki and K.~Stromberg published the following question: {\it Does every infinite compact group have a subgroup which is not Haar measurable?} An affirmative answer is given for all compact groups with the exception of some…

Group Theory · Mathematics 2014-06-27 Salvador Hernández , Karl H. Hofmann , Sidney A. Morris

Generalizing results from \cite{DTk,DU} we study the fine structure of locally minimal (locally) precompact Abelian groups (these are the locally essential subgroups $G$ of LCA groups $L$, i.e., such that $G$ non-trivially meets all…

Group Theory · Mathematics 2025-10-21 Dikran Dikranjan , Wei He , Dekui Peng

We characterize when the countable power of a Corson compactum has a dense metrizable subspace and construct consistent examples of Corson compacta whose countable power does not have a dense metrizable subspace. We also give several…

General Topology · Mathematics 2024-03-26 Arkady Leiderman , Santi Spadaro , Stevo Todorcevic

A metric space is plastic if all its non-expansive bijections are isometries. We prove three main results: (1) every countable dense subspace of a normed space is not plastic, (2) every $k$-crowded separable metric space contains a plastic…

General Topology · Mathematics 2026-01-05 Taras Banakh , Oles Mazurenko , Olesia Zavarzina

This book offers to study locally compact groups from the point of view of appropriate metrics that can be defined on them, in other words to study "Infinite groups as geometric objects", as Gromov writes it in the title of a famous…

Group Theory · Mathematics 2016-12-01 Yves Cornulier , Pierre de la Harpe

We prove that two countable locally finite-by-abelian groups G,H endowed with proper left-invariant metrics are coarsely equivalent if and only if their asymptotic dimensions coincide and the groups are either both finitely-generated or…

Group Theory · Mathematics 2008-09-30 T. Banakh , J. Higes , I. Zarichinyy

We present a series of examples of nondiscrete reflexive P-groups (i.e., groups in which all $G_\delta$-sets are open) as well as noncompact reflexive $\omega$-bounded groups (in which the closure of every countable set is compact). Our…

General Topology · Mathematics 2016-03-01 Jorge Galindo , Luis Recoder-Nuñez , Mikhail Tkachenko

A topological space is iso-dense if it has a dense set of isolated points. A topological space is scattered if each of its non-empty subspaces has an isolated point. In $\mathbf{ZF}$, in the absence of the axiom of choice, basic properties…

General Topology · Mathematics 2021-01-11 Kyriakos Keremedis , Eleftherios Tachtsis , Eliza Wajch

We investigate which definable separable metric spaces are countable dense homogeneous (CDH). We prove that a Borel CDH space is completely metrizable and give a complete list of zero-dimensional Borel CDH spaces. We also show that for a…

General Topology · Mathematics 2013-10-09 Michael Hrusak , Beatriz Zamora Aviles

A locally compact contraction group is a pair (G,f) where G is a locally compact group and f an automorphism of G which is contractive in the sense that the forward orbit under f of each g in G converges to the neutral element e, as n tends…

Group Theory · Mathematics 2018-04-05 Helge Glockner , George A. Willis

A topological space is reversible if each continuous bijection of it onto itself is open. We introduce an analogue of this notion in the category of topological groups: A topological group G is g-reversible if every continuous automorphism…

Group Theory · Mathematics 2019-12-24 Vitalij Chatyrko , Dmitri Shakhmatov