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Related papers: Projection complexes and quasimedian maps

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Using the projection complex machinery, Bestvina-Bromberg-Fujiwara, Hagen-Petyt and Han-Nguyen-Yang prove that several classes of nonpositively-curved groups admit equivariant quasi-isometric embeddings into finite products of quasi-trees,…

Group Theory · Mathematics 2026-05-06 Bingxue Tao

We prove the equivalence between a relative bottleneck property and being quasi-isometric to a tree-graded space. As a consequence, we deduce that the quasi-trees of spaces defined axiomatically by Bestvina-Bromberg-Fujiwara are…

Metric Geometry · Mathematics 2017-01-26 David Hume

The class of quasi-median graphs is a generalisation of median graphs, or equivalently of CAT(0) cube complexes. The purpose of this thesis is to introduce these graphs in geometric group theory. In the first part of our work, we extend the…

Group Theory · Mathematics 2017-12-06 Anthony Genevois

We say that a finitely generated group $G$ has property (QT) if it acts isometrically on a finite product of quasi-trees so that orbit maps are quasi-isometric embeddings. A quasi-tree is a connected graph with path metric quasi-isometric…

Group Theory · Mathematics 2020-10-15 Mladen Bestvina , Kenneth Bromberg , Koji Fujiwara

A quasi-tree is a geodesic metric space quasi-isometric to a tree. We give a general construction of many actions of groups on quasi-trees. The groups we can handle include non-elementary (relatively) hyperbolic groups, rank 1 CAT(0)…

Group Theory · Mathematics 2014-09-09 Mladen Bestvina , Kenneth Bromberg , Koji Fujiwara

A simplicial graph is said to be (coarsely) Helly if any collection of pairwise intersecting balls has non-empty (coarse) intersection. (Coarsely) Helly groups are groups acting geometrically on (coarsely) Helly graphs. Our main result is…

Group Theory · Mathematics 2024-05-14 Damian Osajda , Motiejus Valiunas

In this paper we provide two new constructions that are useful for the theory of projection complexes developed by Bestvina, Bromberg, Fujiwara and Sisto. We prove that there exists a subtree of the projection complex which is…

Group Theory · Mathematics 2024-12-18 Patrick S. Nairne

In this paper we prove a general structure theorem for relatively hyperbolic groups (with arbitrary peripheral subgroups) acting naive convex co-compactly on properly convex domains in real projective space. We also establish a…

Geometric Topology · Mathematics 2025-12-24 Mitul Islam , Andrew Zimmer

This paper continues a geometric study of Harvey's Complex of Curves, whose ultimate goal is to apply the theory of hyperbolic spaces and groups to algorithmic questions for the Mapping Class Group and geometric properties of Kleinian…

Geometric Topology · Mathematics 2007-05-23 Howard A. Masur , Yair N. Minsky

It is shown that the middle quasi-homomorphisms of Fujiwara and Kapovich are precisely constant perturbations of quasi-homomorphisms. Quasi-polynomial maps are defined and their constructibility is explored. In particular, it is shown that…

Group Theory · Mathematics 2025-06-03 Primoz Moravec

We examine a graph $\Gamma$ encoding the intersection of hyperplane carriers in a CAT(0) cube complex $\widetilde X$. The main result is that $\Gamma$ is quasi-isometric to a tree. This implies that a group $G$ acting properly and…

Group Theory · Mathematics 2015-03-18 Mark F. Hagen

We algebraically characterize free by cyclic groups that have coarse medians, and prove that this is equivalent to the a priori stronger properties of being colourable hierarchically hyperbolic groups and being quasi-isometric to CAT(0)…

Group Theory · Mathematics 2026-05-19 Eliot Bongiovanni , Pritam Ghosh , Funda Gültepe , Mark Hagen

We show that any group that is hyperbolic relative to virtually nilpotent subgroups, and does not admit peripheral splittings, contains a quasi-isometrically embedded copy of the hyperbolic plane. In natural situations, the specific…

Group Theory · Mathematics 2020-11-09 John M. Mackay , Alessandro Sisto

We introduce the extension graph of graph product of groups and study its geometry. This enables us to study properties of graph product by exploiting large scale geometry of its defining graph. In particular, we show that the extension…

Group Theory · Mathematics 2026-03-17 Koichi Oyakawa

We show that colorable hierarchically hyperbolic groups (HHGs) admit asymptotically CAT(0) metrics, that is, roughly, metrics where the CAT(0) inequality holds up to sublinear error in the size of the triangle. We use the asymptotically…

Geometric Topology · Mathematics 2025-04-25 Matthew Gentry Durham , Yair Minsky , Alessandro Sisto

An interesting question about quasiconvexity in a hyperbolic group concerns finding classes of quasiconvex subsets that are closed under finite intersections. A known example is the class of all quasiconvex subgroups. However, not much is…

Group Theory · Mathematics 2007-05-23 Ashot Minasyan

We relate three classes of nonpositively curved metric spaces: hierarchically hyperbolic spaces, coarsely injective spaces, and strongly shortcut spaces. We show that every hierarchically hyperbolic space admits a new metric that is…

Group Theory · Mathematics 2023-06-21 Thomas Haettel , Nima Hoda , Harry Petyt

In the context of CAT(0) cubical groups, we develop an analogue of the theory of curve complexes and subsurface projections. The role of the subsurfaces is played by a collection of convex subcomplexes called a \emph{factor system}, and the…

Geometric Topology · Mathematics 2017-06-14 Jason Behrstock , Mark F. Hagen , Alessandro Sisto

We build quasi--isometry invariants of relatively hyperbolic groups which detect the hyperbolic parts of the group; these are variations of the stable dimension constructions previously introduced by the authors. We prove that, given any…

Group Theory · Mathematics 2016-09-19 Matthew Cordes , David Hume

We provide sufficient conditions for two subgroups of a hierarchically hyperbolic group to generate an amalgamated free product over their intersection. The result applies in particular to certain geometric subgroups of mapping class groups…

Group Theory · Mathematics 2026-01-07 Giorgio Mangioni
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