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This work deals with relations between a bounded cohomological invariant and the geometry of Hermitian symmetric spaces of noncompact type. The invariant, obtained from the K\"ahler class, is used to define and characterize a special class…

Differential Geometry · Mathematics 2007-05-23 Anna Wienhard

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

We study the boundaries of relatively hyperbolic HHGs. Using the simplicial structure on the hierarchically hyperbolic boundary, we characterize both relative hyperbolicity and being thick of order 1 among HHGs. In the case of relatively…

Group Theory · Mathematics 2023-05-29 Carolyn Abbott , Jason Behrstock , Jacob Russell

We introduce properties of metric spaces and, specifically, finitely generated groups with word metrics which we call coarse coherence and coarse regular coherence. They are geometric counterparts of the classical algebraic notion of…

K-Theory and Homology · Mathematics 2020-02-17 Boris Goldfarb , Jonathan L. Grossman

We demonstrate under appropriate finiteness conditions that a coarse embedding induces an inequality of homological Dehn functions. Applications of the main results include a characterization of what finitely presentable groups may admit a…

Geometric Topology · Mathematics 2020-11-19 Robert Kropholler , Mark Pengitore

We show the equivalence of several characterizations of relative hyperbolicity for metric spaces, and obtain extra information about geodesics in a relatively hyperbolic space. We apply this to characterize hyperbolically embedded subgroups…

Group Theory · Mathematics 2012-10-31 Alessandro Sisto

We prove that the mapping class group of a sphere with five punctures admits uncountably many coarsely equivariant coarse median structures. The same is shown for right-angled Artin groups whose defining graphs are connected, triangle- and…

Group Theory · Mathematics 2025-10-20 Giorgio Mangioni

A subgroup $H\leq G$ is said to be almost normal if every conjugate of $H$ is commensurable to $H$. If $H$ is almost normal, there is a well-defined quotient space $G/H$. We show that if a group $G$ has type $F_{n+1}$ and contains an almost…

Group Theory · Mathematics 2021-09-15 Alexander Margolis

A certain Grothendieck topology assigned to a metric space gives rise to a sheaf cohomology theory which sees the coarse structure of the space. Already constant coefficients produce interesting cohomology groups. In degree 0 they see the…

Algebraic Topology · Mathematics 2022-05-04 Elisa Hartmann

We introduce the group-compact coarse structure on a Hausdorff topological group in the context of coarse structures on an abstract group which are compatible with the group operations. We develop asymptotic dimension theory for the…

Geometric Topology · Mathematics 2012-01-24 Andrew Nicas , David Rosenthal

Hierarchically hyperbolic spaces provide a common framework for studying mapping class groups of finite type surfaces, Teichm\"uller space, right-angled Artin groups, and many other cubical groups. Given such a space $\mathcal X$, we build…

Geometric Topology · Mathematics 2018-03-16 Matthew G. Durham , Mark F. Hagen , Alessandro Sisto

We study the geometry of nonrelatively hyperbolic groups. Generalizing a result of Schwartz, any quasi-isometric image of a non-relatively hyperbolic space in a relatively hyperbolic space is contained in a bounded neighborhood of a single…

Geometric Topology · Mathematics 2010-04-13 Jason Behrstock , Cornelia Drutu , Lee Mosher

Hierarchically hyperbolic spaces (HHSs) are a large class of spaces that provide a unified framework for studying the mapping class group, right-angled Artin and Coxeter groups, and many 3--manifold groups. We investigate strongly…

Group Theory · Mathematics 2021-06-18 Jacob Russell , Davide Spriano , Hung Cong Tran

In this note on coarse geometry we revisit coarse homotopy. We prove that coarse homotopy indeed is an equivalence relation, and this in the most general context of abstract coarse structures. We introduce (in a geometric way) coarse…

Geometric Topology · Mathematics 2023-08-14 Paul D. Mitchener , Behnam Norouzizadeh , Thomas Schick

We introduce the notion of tight homomorphism into a locally compact group with nonvanishing bounded cohomology and study these homomorphisms in detail when the target is a Lie group of Hermitian type. Tight homomorphisms between Lie groups…

Differential Geometry · Mathematics 2008-09-15 Marc Burger , Alessandra Iozzi , Anna Wienhard

We study the subgroup structure of discrete groups which share cohomological properties which resemble non-negative curvature. Examples include all Gromov hyperbolic groups. We provide strong restrictions on the possible s-normal subgroups…

Group Theory · Mathematics 2008-10-13 Andreas Thom

We systematically investigate cocycle superrigidity in the setting of finite rank median spaces for product groups and Kazhdan groups. By employing a dynamical approach to superrigidity, we establish, for a median space X of finite rank,…

Metric Geometry · Mathematics 2025-07-22 Biao Ma , Lamine Messaci

We generalize a result of Paulin on the Gromov boundary of hyperbolic groups to the Morse boundary of proper, maximal hierarchically hyperbolic spaces admitting cocompact group actions by isometries. Namely we show that if the Morse…

Geometric Topology · Mathematics 2018-01-16 Sarah C. Mousley , Jacob Russell

We develop a theory of large scale geometry of metrisable topological groups that, in a significant number of cases, allows one to define and identify a unique quasi-isometry type intrinsic to the topological group. Moreover, this…

Group Theory · Mathematics 2014-03-14 Christian Rosendal

The class of coarsely convex spaces is a coarse geometric analogue of the class of nonpositively curved Riemannian manifolds. It includes Gromov hyperbolic spaces, CAT(0) spaces, proper injective metric spaces and systolic complexes. It is…

Metric Geometry · Mathematics 2024-02-20 Yuuhei Ezawa , Tomohiro Fukaya