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Let G be a one-ended group acting discretely and co-compactly on a CAT(0) space X. We show that the boundary of X has no cut points and that one can detect splittings of $G$ over two-ended groups and recover its JSJ decomposition from the…

Group Theory · Mathematics 2008-12-18 Panos Papasoglu , Eric Swenson

We prove that bounded conciseness is a closed property in the space of marked groups. As a consequence, we reformulate a conjecture of Fern\'andez-Alcober and Shumyatsky [7] about conciseness in the class of residually finite groups.

Group Theory · Mathematics 2025-02-10 Federico Berlai

We classify topological $4$-manifolds with boundary and fundamental group $\mathbb{Z}$, under some assumptions on the boundary. We apply this to classify surfaces in simply-connected $4$-manifolds with $S^3$ boundary, where the fundamental…

Geometric Topology · Mathematics 2024-08-21 Anthony Conway , Lisa Piccirillo , Mark Powell

We explain how to adapt a construction of M. Sageev's to construct a proper action on a CAT(0) cube complex starting from a proper action on a wall space, and use this to deduce that if G is a group containing an amenable subgroup H of…

Geometric Topology · Mathematics 2007-05-23 I. L. Chatterji , G. A. Niblo

The concept of quasi-partial b-metric-like spaces is being introduced and studied with the help of topology. Examples are also discussed to support the results. Some fixed point theorems are proved in the setting of quasi-partial…

General Topology · Mathematics 2018-12-04 Anuradha Gupta , Manu Rohilla

For a given bundle $\xi \colon E \to M$ over a manifold, configuration-section spaces on $\xi$ parametrise finite subsets $z \subseteq M$ equipped with a section of $\xi$ defined on $M \smallsetminus z$, with prescribed "charge" in a…

Algebraic Topology · Mathematics 2021-09-03 Martin Palmer , Ulrike Tillmann

In this paper we introduce congruence spaces, which are topological spaces that are canonically attached to monoid schemes and that reflect closed topological properties. This leads to satisfactory topological characterizations of closed…

Algebraic Geometry · Mathematics 2023-05-23 Oliver Lorscheid , Samarpita Ray

We develop the notion of a geometric covering of a rigid space X, which yields a much larger class of covering spaces than that studied previously by de Jong. Geometric coverings of X are closed under disjoint unions and are \'etale local…

Algebraic Geometry · Mathematics 2022-03-24 Piotr Achinger , Marcin Lara , Alex Youcis

We prove that finitely generated amenable groups acting on CAT(0) spaces satisfy the following alternative: either every action on a geodesically complete CAT(0) space with bounded geometry (or finite dimension) has a global fixed point, or…

Group Theory · Mathematics 2026-03-30 Hiroyasu Izeki , Ran Ji , Anders Karlsson , Yunhui Wu

This is an expository survey with two goals. 1) The primary goal is to discuss and highlight the impact of two recent influential ideas in geometric group theory. The first of which is the notion of an injective metric space which is a rich…

Group Theory · Mathematics 2023-05-05 Abdul Zalloum

In this paper we consider discrete groups in ${\rm PGL}_d(\mathbb{R})$ acting convex co-compactly on a properly convex domain in real projective space. For such groups, we establish necessary and sufficient conditions for the group to be…

Geometric Topology · Mathematics 2023-05-24 Mitul Islam , Andrew Zimmer

We study geometric and topological properties of locally compact, geodesically complete spaces with an upper curvature bound. We control the size of singular subsets, discuss homotopical and measure-theoretic stratifications and regularity…

Differential Geometry · Mathematics 2018-07-19 Alexander Lytchak , Koichi Nagano

This article is a survey article on geometric group theory from the point of view of a non-expert who likes geometric group theory and uses it in his own research. The sections are: classical examples, basics about quasiisometry,properties…

Group Theory · Mathematics 2008-09-11 Wolfgang Lueck

We provide new stable linearizability constructions for regular actions of finite groups on homogeneous spaces and low-dimensional quadrics.

Algebraic Geometry · Mathematics 2024-11-04 Brendan Hassett , Yuri Tschinkel

In this work we present a principle which says that quasimorphisms can be obtained via "local data" of the group action on certain appropriate spaces. In a rough manner the principle says that instead of starting with a given group and try…

Group Theory · Mathematics 2012-01-31 Gabi Ben Simon

In this paper we study the spaces of $q$-tuples of points in a Euclidean space, without $k$-wise coincidences (configuration-like spaces). A transitive group action by permuting these points is considered, and some new upper bounds on the…

Algebraic Topology · Mathematics 2014-10-01 R. N. Karasev , A. Yu. Volovikov

This paper is partly a survey of known results on quadratic forms that are hard to find in the literature. Our main focus is a twisted form of a construction due to Bezout. This skew Bezoutian is a symplectic (resp. quadratic) space…

Commutative Algebra · Mathematics 2013-09-13 Florent Jouve , Fernando Rodriguez-Villegas

We study the possibility of applying a finite-dimensionality argument in order to address parts of the Baum-Connes conjecture for finitely generated linear groups. This gives an alternative approach to the results of Guentner, Higson, and…

Geometric Topology · Mathematics 2007-05-23 Dmitry Matsnev

We construct explicitly a class of coboundary Poisson-Lie structures on the group of formal diffeomorphisms of ${\Bbb R}^n$. Equivalently, these give rise to a class of coboundary triangular Lie bialgebra structures on the Lie algebra $W_n$…

Quantum Algebra · Mathematics 2007-05-23 Ognyan S. Stoyanov

We examine a condition on a simply connected 2-complex X ensuring that groups acting properly on X are coherent. This extends earlier work on 2-complexes with negative sectional curvature which covers the case that G acts freely. Our…

Group Theory · Mathematics 2016-02-17 Eduardo Martínez-Pedroza , Daniel T. Wise