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Search Results: 1 - 10 of 3445 matches for " Ruth Charney "
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An introduction to right-angled Artin groups
Ruth Charney
Mathematics , 2006,
Abstract: Recently, right-angled Artin groups have attracted much attention in geometric group theory. They have a rich structure of subgroups and nice algorithmic properties, and they give rise to cubical complexes with a variety of applications. This survey article is meant to introduce readers to these groups and to give an overview of the relevant literature.
Automorphisms of higher-dimensional right-angled Artin groups
Ruth Charney,Karen Vogtmann
Mathematics , 2007,
Abstract: We study the algebraic structure of the automorphism group of a general right-angled Artin group. We show that this group is virtually torsion-free and has finite virtual cohomological dimension. This generalizes results proved by the authors and John Crisp (arXiv:math/0610980) for two-dimensional right-angled Artin groups.
Random groups arising as graph products
Ruth Charney,Michael Farber
Mathematics , 2010, DOI: 10.2140/agt.2012.12.979
Abstract: In this paper we study the hyperbolicity properties of a class of random groups arising as graph products associated to random graphs. Recall, that the construction of a graph product is a generalization of the constructions of right-angled Artin and Coxeter groups. We adopt the Erdos - Renyi model of a random graph and find precise threshold functions for the hyperbolicity (or relative hyperbolicity). We aslo study automorphism groups of right-angled Artin groups associated to random graphs. We show that with probability tending to one as $n\to \infty$, random right-angled Artin groups have finite outer automorphism groups, assuming that the probability parameter $p$ is constant and satisfies $0.2929
Length functions of 2-dimensional right-angled Artin groups
Ruth Charney,Max Margolis
Mathematics , 2011,
Abstract: Morgan and Culler proved that a minimal action of a free group on a tree is determined by its translation length function. We prove an analogue of this theorem for 2-dimensional right-angled Artin groups acting on CAT(0) rectangle complexes.
Metric characterizations of spherical, and Euclidean buildings
Ruth Charney,Alexander Lytchak
Mathematics , 2001, DOI: 10.2140/gt.2001.5.521
Abstract: A building is a simplicial complex with a covering by Coxeter complexes (called apartments) satisfying certain combinatorial conditions. A building whose apartments are spherical (respectively Euclidean) Coxeter complexes has a natural piecewise spherical (respectively Euclidean) metric with nice geometric properties. We show that spherical and Euclidean buildings are completely characterized by some simple, geometric properties.
Subgroups and quotient groups of automorphism groups of RAAGs
Ruth Charney,Karen Vogtmann
Mathematics , 2009,
Abstract: We study subgroups and quotients of outer automorphism groups of right-angled Artin groups (RAAGs). We prove that for all RAAGS, the outer automorphism group is residually finite and, for a large class of RAAGs, it satisfies the Tits alternative. We also investigate which of these automorphism groups contain non-abelian solvable subgroups.
Relative hyperbolicity and Artin groups
Ruth Charney,John Crisp
Mathematics , 2006,
Abstract: This paper considers the question of relative hyperbolicity of an Artin group with regard to the geometry of its associated Deligne complex. We prove that an Artin group is weakly hyperbolic relative to its finite (or spherical) type parabolic subgroups if and only if its Deligne complex is a Gromov hyperbolic space. For a 2-dimensional Artin group the Deligne complex is Gromov hyperbolic precisely when the corresponding Davis complex is Gromov hyperbolic, that is, precisely when the underlying Coxeter group is a hyperbolic group. For Artin groups of FC type we give a sufficient condition for hyperbolicity of the Deligne complex which applies to a large class of these groups for which the underlying Coxeter group is hyperbolic.
Divergence and quasimorphisms of right-angled Artin groups
Jason Behrstock,Ruth Charney
Mathematics , 2010,
Abstract: We give a group theoretic characterization of geodesics with superlinear divergence in the Cayley graph of a right-angled Artin group A(G) with connected defining graph G. We use this to determine when two points in an asymptotic cone of A(G) are separated by a cut-point. As an application, we show that if G does not decompose as the join of two subgraphs, then A(G) has an infinite-dimensional space of non-trivial quasimorphisms. By the work of Burger and Monod, this leads to a superrigidity theorem for homomorphisms from lattices into right-angled Artin groups.
Convexity of parabolic subgroups in Artin groups
Ruth Charney,Luis Paris
Mathematics , 2014,
Abstract: We prove that any standard parabolic subgroup of any Artin group is convex with respect to the standard generating set.
Contracting Boundaries of CAT(0) Spaces
Ruth Charney,Harold Sultan
Mathematics , 2013,
Abstract: As demonstrated by Croke and Kleiner, the visual boundary of a CAT(0) group is not well-defined since quasi-isometric CAT(0) spaces can have non-homeomorphic boundaries. We introduce a new type of boundary for a CAT(0) space, called the contracting boundary, made up rays satisfying one of five hyperbolic-like properties. We prove that these properties are all equivalent and that the contracting boundary is a quasi-isometry invariant. We use this invariant to distinguish the quasi-isometry classes of certain right-angled Coxeter groups.
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