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We show that given a quasi-circle $C$ in $\partial_{\infty}\mathbb{H}^3$ (respectively in $\partial_{\infty} \mathbb{ADS}^3$) and a complete conformal metric $h$ on $\mathbb{D}$ whose curvature $K_h$ takes values in a compact subset of…

Differential Geometry · Mathematics 2025-10-28 Abderrahim Mesbah

Learning fine-grained embeddings from coarse labels is a challenging task due to limited label granularity supervision, i.e., lacking the detailed distinctions required for fine-grained tasks. The task becomes even more demanding when…

Computer Vision and Pattern Recognition · Computer Science 2023-11-21 Shu-Lin Xu , Yifan Sun , Faen Zhang , Anqi Xu , Xiu-Shen Wei , Yi Yang

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 give several sufficient conditions for uniform exponential growth in the setting of virtually torsion-free hierarchically hyperbolic groups. For example, any hierarchically hyperbolic group that is also acylindrically hyperbolic has…

Group Theory · Mathematics 2021-11-05 Carolyn Abbott , Thomas Ng , Davide Spriano , Radhika Gupta , Harry Petyt

We introduce a class of metric spaces which we call "bolic". They include hyperbolic spaces, simply conneccted complete manifolds of nonpositive curvature, euclidean buildings, etc. We prove the Novikov conjecture on higher signatures for…

Algebraic Geometry · Mathematics 2007-05-23 Gennadi Kasparov , Georges Skandalis

The rank of a hierarchically hyperbolic space is the maximal number of unbounded factors in a standard product region. For hierarchically hyperbolic groups, this coincides with the maximal dimension of a quasiflat. Examples for which the…

Geometric Topology · Mathematics 2020-08-25 Jason Behrstock , Mark F Hagen , Alessandro Sisto

Let M be a compact hyperbolic manifold with totally geodesic boundary. If the injectivity radius of the boundary is larger than an explicit function of the normal injectivity radius of the boundary, we show that there is a negatively curved…

Geometric Topology · Mathematics 2026-01-27 Colby Kelln , Jason Manning

We show that any infinite order element $g$ of a virtually cyclic hyperbolically embedded subgroup of a group $G$ is Morse, that is to say any quasi-geodesic connecting points in the cyclic group $C$ generated by $g$ stays close to $C$.…

Group Theory · Mathematics 2013-10-30 Alessandro Sisto

Injective metric spaces, or absolute 1-Lipschitz retracts, share a number of properties with CAT(0) spaces. In the 1960es, J. R. Isbell showed that every metric space X has an injective hull E(X). Here it is proved that if X is the vertex…

Group Theory · Mathematics 2012-06-29 Urs Lang

We prove that the hierarchical hull of any finite set of interior points, hierarchy rays, and boundary points in a hierarchically hyperbolic space (HHS) is quasi-median quasi-isometric to a CAT(0) cube complex of bounded dimension. Our…

Group Theory · Mathematics 2023-08-29 Matthew Gentry Durham

Behrstock, Hagen, and Sisto classified 3-manifold groups admitting a hierarchically hyperbolic space structure. However, these structures were not always equivariant with respect to the group. In this paper, we classify 3-manifold groups…

Geometric Topology · Mathematics 2023-08-14 Mark Hagen , Jacob Russell , Alessandro Sisto , Davide Spriano

In this work, we are concerned with hierarchically hyperbolic spaces and hierarchically hyperbolic groups. Our main result is a wide generalization of a combination theorem of Behrstock, Hagen, and Sisto. In particular, as a consequence, we…

Group Theory · Mathematics 2019-09-25 Federico Berlai , Bruno Robbio

This is an expository survey with two goals. 1) The primary goal is to discuss and highlight the impact of two recent influential ideas in geometric group theory. The first of which is the notion of an injective metric space which is a rich…

Group Theory · Mathematics 2023-05-05 Abdul Zalloum

We show that quasi-isometries of (well-behaved) hierarchically hyperbolic groups descend to quasi-isometries of their maximal hyperbolic space. This has two applications, one relating to quasi-isometry invariance of acylindrical…

Group Theory · Mathematics 2025-01-08 Antoine Goldsborough , Mark Hagen , Harry Petyt , Jacob Russell , Alessandro Sisto

We introduce and study the notions of hyperbolically embedded and very rotating families of subgroups. The former notion can be thought of as a generalization of the peripheral structure of a relatively hyperbolic group, while the later one…

Group Theory · Mathematics 2021-04-02 F. Dahmani , V. Guirardel , D. Osin

We introduce the separating semigroup of a real algebraic curve of dividing type. The elements of this semigroup record the possible degrees of the covering maps obtained by restricting separating morphisms to the real part of the curve. We…

Algebraic Geometry · Mathematics 2020-08-04 Mario Kummer , Kristin Shaw

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 study relations between maps between relatively hyperbolic groups/spaces and quasisymmetric embeddings between their boundaries. More specifically, we establish a correspondence between (not necessarily coarsely surjective)…

Geometric Topology · Mathematics 2025-05-14 John M. Mackay , Alessandro Sisto

Let G be a graph of hyperbolic groups with 2-ended edge groups. We show that G is hierarchically hyperbolic if and only if G has no distorted infinite cyclic subgroup. More precisely, we show that G is hierarchically hyperbolic if and only…

Group Theory · Mathematics 2020-07-28 Bruno Robbio , Davide Spriano

We suggest a new approach to the study of relatively hyperbolic groups based on relative isoperimetric inequalities. Various geometric, algebraic, and algorithmic properties are discussed.

Group Theory · Mathematics 2015-01-29 D. V. Osin