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Related papers: Cross ratios on ${\rm CAT(0)}$ cube complexes and …

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We introduce a $\mathbb{Z}$-valued cross ratio on Roller boundaries of ${\rm CAT(0)}$ cube complexes. We motivate its relevance by showing that every cross-ratio preserving bijection of Roller boundaries uniquely extends to a cubical…

Geometric Topology · Mathematics 2022-01-28 Jonas Beyrer , Elia Fioravanti , Merlin Incerti-Medici

We revisit the topic of probability measures on CAT(0) cube complexes and prove that an amenable group acting on a CAT(0) cube complex, regardless of dimension, necessarily preserves an interval in the Roller compactification. In the finite…

Group Theory · Mathematics 2024-03-26 Talia Fernós

Many geometric structures associated to surface groups can be encoded in terms of invariant cross ratios on their circle at infinity; examples include points of Teichm\"uller space, Hitchin representations and geodesic currents. We add to…

Geometric Topology · Mathematics 2026-03-25 Jonas Beyrer , Elia Fioravanti

Culler and Morgan proved that the length function of a minimal action of a group on a tree completely determines the action. As a consequence the space of minimal actions of a free group on trees, up to scaling (also known as Outer Space),…

Group Theory · Mathematics 2015-10-21 Anna Vijayan

We study uniform exponential growth of groups acting on CAT(0) cube complexes. We show that groups acting without global fixed points on CAT(0) square complexes either have uniform exponential growth or stabilize a Euclidean subcomplex.…

Group Theory · Mathematics 2023-04-05 Radhika Gupta , Kasia Jankiewicz , Thomas Ng

We define a bounded cohomology class, called the {\em median class}, in the second bounded cohomology -- with appropriate coefficients --of the automorphism group of a finite dimensional CAT(0) cube complex X. The median class of X behaves…

Group Theory · Mathematics 2015-08-10 Indira Chatterji , Talia Fernós , Alessandra Iozzi

We prove that any group acting essentially without a fixed point at infinity on an irreducible finite-dimensional CAT(0) cube complex contains a rank one isometry. This implies that the Rank Rigidity Conjecture holds for CAT(0) cube…

Group Theory · Mathematics 2013-04-19 Pierre-Emmanuel Caprace , Michah Sageev

We construct new families of quasimorphisms on many groups acting on CAT(0) cube complexes. These quasimorphisms have a uniformly bounded defect of 12, and they "see" all elements that act hyperbolically on the cube complex. We deduce that…

Group Theory · Mathematics 2018-06-29 Talia Fernós , Max Forester , Jing Tao

In this paper we start the inquiry into proving uniform exponential growth in the context of groups acting on CAT(0) cube complexes. We address free group actions on CAT(0) square complexes and prove a more general statement. This says that…

Group Theory · Mathematics 2019-05-29 Aditi Kar , Michah Sageev

We expand the class of groups with relatively geometric actions on CAT(0) cube complexes by proving that it is closed under $C'(\frac16)$--small cancellation free products. We build upon a result of Martin and Steenbock who prove an…

Group Theory · Mathematics 2024-10-11 Eduard Einstein , Thomas Ng

We compare the marked length spectra of some pairs of proper and cocompact cubical actions of a non-virtually cyclic group on $\text{CAT}(0)$ cube complexes. The cubulations are required to be virtually co-special, have the same sets of…

Group Theory · Mathematics 2024-06-26 Stephen Cantrell , Eduardo Reyes

In this paper, we study topological dynamics on the visual boundary and several combinatorial boundaries associated to $\operatorname{CAT}(0)$ spaces. Through verifying the freeness of Myrberg points on the boundaries, we prove that a large…

Group Theory · Mathematics 2025-10-08 Xin Ma , Daxun Wang , Wenyuan Yang

We obtain a sufficient condition for lattices in the automorphism group of a finite dimensional CAT(0) cube complex to have infinite girth. As a corollary, we get a version of Girth Alternative for groups acting geometrically: any such…

Group Theory · Mathematics 2024-08-20 Arka Banerjee , Daniel Gulbrandsen , Pratyush Mishra , Prayagdeep Parija

In this paper, we study boundary actions of CAT(0) spaces from a point of view of topological dynamics and $C^*$-algebras. First, we investigate the actions of right-angled Coexter groups and right-angled Artin groups with finite defining…

Operator Algebras · Mathematics 2022-03-01 Xin Ma , Daxun Wang

Finite rank median spaces are a simultaneous generalisation of finite dimensional ${\rm CAT}(0)$ cube complexes and real trees. If $\Gamma$ is an irreducible lattice in a product of rank one simple Lie groups, we show that every action of…

Geometric Topology · Mathematics 2019-07-02 Elia Fioravanti

We investigate the cocompact action of Higman's group on a CAT(0) square complex associated to its standard presentation. We show that this action is in a sense intrinsic, which allows for the use of geometric techniques to study the…

Group Theory · Mathematics 2017-03-15 Alexandre Martin

We exhibit a variety of groups that act properly and even cocompactly on median graphs (a.k.a. one-skeletons of CAT(0) cube complexes), with quasi-isometric groups that do not admit any proper action on a median graph. This answes a…

Group Theory · Mathematics 2023-05-10 Francesco Fournier-Facio , Anthony Genevois

The Roller boundary is a well-known compactification of a CAT(0) cube complex X. When X is locally finite, essential, irreducible, non-Euclidean and admits a cocompact action by a group G, Nevo-Sageev show that a subset, B(X), of the Roller…

Geometric Topology · Mathematics 2021-01-11 Ivan Levcovitz

In [4], Dunwoody defined resolutions for finitely presented group actions on simplicial trees, that is, an action of the group on a tree with smaller edge and vertex stabilizers. He, moreover, proved that the size of the resolution is…

Group Theory · Mathematics 2016-09-21 Benjamin Beeker , Nir Lazarovich

We prove that almost all arc complexes do not admit a CAT(0) metric with finitely many shapes, in particular any finite-index subgroup of the mapping class group does not preserve such a metric on the arc complex. We also show the analogous…

Geometric Topology · Mathematics 2020-04-21 Richard C. H. Webb
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