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Related papers: Topological matchings and amenability

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We show that the topological full group of a Hausdorff ample groupoid with compact unit space coincides with the group of homotopy classes of invertible isometries in pseudofunction algebras associated with the groupoid. Moreover, if the…

Operator Algebras · Mathematics 2025-11-19 Eusebio Gardella , Mathias Palmstrøm , Hannes Thiel

For locally compact groups amenability and Kazhdan's property (T) are mutually exclusive in the sense that a group having both properties is compact. This is no longer true for more general Polish groups. However, a weaker result still…

Group Theory · Mathematics 2021-02-18 Vladimir G. Pestov

We classify the possible elementary amenable fundamental groups of compact aspherical 4-manifolds with boundary and conclude that they are either polycyclic or solvable Baumslag- Solitar. Since these groups are good and satisfy the…

Geometric Topology · Mathematics 2025-01-23 James F. Davis , J. A. Hillman

We study manifolds endowed with an (almost) even Clifford (hermitian) structure and admitting a large automorphism group. We classify them when they are simply connected and the dimension of the automorphism group is maximal, and also prove…

Differential Geometry · Mathematics 2016-06-07 Gerardo Arizmendi , Rafael Herrera , Noemi Santana

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

A topological group $G$ is {\em extremely amenable} if every compact $G$-space has a $G$-fixed point. Let $X$ be compact and $G\subset{\mathrm{Homeo}} (X)$. We prove that the following are equivalent: (1) $G$ is extremely amenable; (2)…

Dynamical Systems · Mathematics 2021-08-27 Vladimir Uspenskij

We undertake a systematic study of the approximation properties of the topological and measurable versions of the coarse boundary groupoid associated to a sequence of finite graphs of bounded degree. On the topological side, we prove that…

Group Theory · Mathematics 2021-12-30 Vadim Alekseev , Leonardo Biz

We show that any second-countable \'etale groupoid with polynomial growth is topologically amenable. If its unit space is compact and metrizable, we show that the groupoid has weak $m$-comparison. Thus if the groupoid is also ample and…

Dynamical Systems · Mathematics 2026-05-18 Are Austad , Christian Bönicke

The purpose of this article is prove that Thompson's group F is amenable. The methods developed will then be used to prove a generalization of Hindman's theorem for the free nonassociative binary system on one generator.

Group Theory · Mathematics 2012-10-02 Justin Tatch Moore

Almost forty years ago, Connes, Feldman and Weiss proved that for measurable equivalence relations the notions of amenability and hyperfiniteness coincide. In this paper we define the uniform version of amenability and hyperfiniteness for…

Dynamical Systems · Mathematics 2020-08-25 Gábor Elek

We initiate a quantitative study of measure equivalence (and orbit equivalence) between finitely generated groups, which extends the classical setting of $\mathrm L^p$ measure equivalence. In this paper, our main focus will be on amenable…

Group Theory · Mathematics 2022-04-18 Thiebout Delabie , Juhani Koivisto , François Le Maître , Romain Tessera

Averaging linear functional on the space continuous functions of the group of diffeomorphisms of interval is found. Amenability of several discrete subgroups of the group of diffeomorphisms $\Diff^3([0,1])$ of interval is prove. In…

Group Theory · Mathematics 2011-01-17 E. T. Shavgulidze

We introduce the notions of definable amenability and extreme definable amenability for groups in continuous structures and conduct an extensive analysis of them, drawing parallels with the classical first-order case. We characterize both…

Logic · Mathematics 2025-04-03 Juan Felipe Carmona , Alf Onshuus

In this paper we study unimodular amenable groups. The first part is devoted to results on the existence of uniform families of epsilon-quasi tilings for these groups. In this context, constructions of Ornstein and Weiss are extended by…

Spectral Theory · Mathematics 2013-07-31 Felix Pogorzelski , Fabian Schwarzenberger

We study amenability of definable and topological groups. Among our main technical tools is an elaboration on and strengthening of the Massicot-Wagner version of the stabilizer theorem, and some results around measures. As an application we…

Logic · Mathematics 2021-11-23 Ehud Hrushovski , Krzysztof Krupiński , Anand Pillay

We give strengthened versions of the Herwig-Lascar and Hodkinson-Otto extension theorems for partial automorphisms of finite structures. Such strengthenings yield several combinatorial and group-theoretic consequences for homogeneous…

Logic · Mathematics 2019-04-17 Daoud Siniora , Sławomir Solecki

We show that amenability of a group acting by homeomorphisms can be deduced from a certain local property of the action and recurrency of the orbital Schreier graphs. This covers amenability of a wide class groups, the amenability of which…

Group Theory · Mathematics 2017-10-05 Kate Juschenko , Volodymyr Nekrashevych , Mikael de la Salle

Autostackability for finitely presented groups is a topological property of the Cayley graph combined with formal language theoretic restrictions, that implies solvability of the word problem. The class of autostackable groups is known to…

Group Theory · Mathematics 2015-06-02 Mark Brittenham , Susan Hermiller , Ashley Johnson

We introduce and geometrically characterize the notion of uniformly perfect Morse boundary for proper geodesic metric spaces. As a unifying result, we prove that the Morse boundary of any finitely generated, non-elementary group is…

Group Theory · Mathematics 2026-02-09 Suzhen Han , Qing Liu

A topological group $G$ has the Approximate Fixed Point (AFP) property on a bounded convex subset $C$ of a locally convex space if every continuous affine action of $G$ on $C$ admits a net $(x_i)$, $x_i\in C$, such that…

Group Theory · Mathematics 2021-02-18 Cleon S. Barroso , Brice R. Mbombo , Vladimir G. Pestov