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We show that the mapping torus of a hyperbolic group by a hyperbolic automorphism is cubulable. Along the way, we (i) give an alternate proof of Hagen and Wise's theorem that hyperbolic free-by-cyclic groups are cubulable, and (ii) extend…

Group Theory · Mathematics 2025-01-08 François Dahmani , Suraj Krishna M S , Jean Pierre Mutanguha

We describe a group theoretic condition which ensures that any cellular action of a group satisfying this condition on a CAT(0) cube complex has a global fixed point. In particular, we show that this fixed point criterion is satisfied by…

Group Theory · Mathematics 2018-05-14 Olga Varghese

We provide a systematic description of the automorphism groups of specially cocompact CAT(0) cube complexes. We show that these groups are topologically finitely generated, present a method to explicitly obtain generating sets, and prove a…

Group Theory · Mathematics 2023-12-07 Tobias Hartnick , Merlin Incerti-Medici

We introduce the notion of an EZ-structure on a group. Delta-hyperbolic groups and CAT(0)-groups have EZ-structures. We show torsion-free groups having an EZ-structure automatically have an action by homeomorphisms on a closed…

Geometric Topology · Mathematics 2007-05-23 F. T. Farrell , J. -F. Lafont

Mahan Mitra (Mj) proved Cannon--Thurston maps exist for normal hyperbolic subgroups of a hyperbolic group. We prove that Cannon--Thurston maps do not exist for infinite normal hyperbolic subgroups of non-hyperbolic CAT(0) groups with…

Geometric Topology · Mathematics 2019-11-13 Benjamin Beeker , Matthew Cordes , Giles Gardam , Radhika Gupta , Emily Stark

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

Let X be a proper CAT(0) cube complex admitting a proper cocompact action by a group G. We give three conditions on the action, any one of which ensures that X has a factor system in the sense of [BHS14]. We also prove that one of these…

Group Theory · Mathematics 2020-01-29 Mark F Hagen , Tim Susse

We construct examples of free-by-cyclic hyperbolic groups which fiber in infinitely many ways over Z. The construction involves adding a specialized square 2-cell to a non-positively curved, squared 2-complex defined by labeled oriented…

Group Theory · Mathematics 2014-11-11 TaraLee Mecham , Antara Mukherjee

For group actions on hyperbolic CAT(0) square complexes, we show that the acylindricity of the action is equivalent to a weaker form of acylindricity phrased purely in terms of stabilisers of points, which has the advantage of being much…

Group Theory · Mathematics 2015-09-11 Alexandre Martin

We define strict C(n) small-cancellation complexes, intermediate to C(n) and C(n+1), and we prove groups acting properly cocompactly on a simply-connected strict C(6) complex are hyperbolic relative to a collection of maximal virtually free…

Group Theory · Mathematics 2025-05-28 Zachary Munro , Daniel T. Wise

Shephard groups are common generalizations of Coxeter groups, Artin groups, and graph products of cyclic groups. Their definition is similar to that of a Coxeter group, but generators may have arbitrary order rather than strictly order 2.…

Group Theory · Mathematics 2024-12-19 Katherine Goldman

We prove the Borel Conjecture for a class of groups containing word-hyperbolic groups and groups acting properly, isometrically and cocompactly on a finite dimensional CAT(0)-space.

Geometric Topology · Mathematics 2010-03-26 Arthur Bartels , Wolfgang Lueck

We prove that many relatively hyperbolic groups obtained by relative strict hyperbolization admit a cocompact action on a CAT(0) cubical complex. Under suitable assumptions on the peripheral subgroups, these groups are residually finite and…

Group Theory · Mathematics 2025-04-04 Daniel Groves , Jean-François Lafont , Jason Fox Manning , Lorenzo Ruffoni

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

Through highly non-constructive methods, works by Bestvina, Culler, Feighn, Morgan, Paulin, Rips, Shalen, and Thurston show that if a finitely presented group does not split over a virtually solvable subgroup, then the space of its discrete…

Geometric Topology · Mathematics 2009-02-17 Yvonne Lai

Given a CAT(0) cube complex X, we show that if Aut(X) $\neq$ Isom(X) then there exists a full subcomplex of X which decomposes as a product with $\mathbb{R}^n$. As applications, we prove that if X is $\delta$-hyperbolic, cocompact and…

Geometric Topology · Mathematics 2017-12-14 Corey Bregman

A generic finite presentation defines a word hyperbolic group whose boundary is homeomorphic to the Menger curve. In this article, we produce the first known examples of non-hyperbolic $CAT(0)$ groups whose visual boundary is homeomorphic…

Group Theory · Mathematics 2020-05-18 Matthew Haulmark , G. Christopher Hruska , Bakul Sathaye

It is well known that every word hyperbolic group has a well-defined visual boundary. An example of C. Croke and B. Kleiner shows that the same cannot be said for CAT(0) groups. All boundaries of a CAT(0) group are, however, shape…

Group Theory · Mathematics 2008-07-31 Christopher Mooney

We give a criterion in terms of the boundary for the existence of a proper cocompact action of a word-hyperbolic group on a CAT(0) cube complex. We describe applications towards lattices and hyperbolic 3-manifold groups. In particular, by…

Geometric Topology · Mathematics 2010-02-17 Nicolas Bergeron , Daniel T. Wise

We show that the Hilbert space compression of any finite dimensional CAT(0) cube complex is 1 and deduce that any discrete group acting properly, co-compactly on a CAT(0) cube complex is exact. The class of groups covered by this theorem…

Group Theory · Mathematics 2007-05-23 Sarah J. Campbell , Graham A. Niblo