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Related papers: Cannon-Thurston maps do not always exist

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We show that the Morse boundary exhibits interesting examples of both the existence and non-existence of Cannon-Thurston maps for normal subgroups, in contrast with the hyperbolic case.

Geometric Topology · Mathematics 2024-11-20 Ruth Charney , Matthew Cordes , Antoine Goldsborough , Alessandro Sisto , Stefanie Zbinden

There is a family of hyperbolic groups known as hyperbolic hydra which contain heavily distorted free subgroups. We prove the existence of Cannon--Thurston maps (that is, maps of the boundaries induced by subgroup inclusion) for these free…

Group Theory · Mathematics 2018-06-07 Owen Baker , Timothy Riley

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 give an overview of the theory of Cannon-Thurston maps which forms one of the links between the complex analytic and hyperbolic geometric study of Kleinian groups. We also briefly sketch connections to hyperbolic subgroups of hyperbolic…

Geometric Topology · Mathematics 2017-12-05 Mahan Mj

For a hyperbolic subgroup H of a hyperbolic group G, we describe sufficient criteria to guarantee the following. 1) Geodesic rays in H starting at the identity land at a unique point of the boundary of G. 2)The inclusion of H into G does…

Geometric Topology · Mathematics 2025-03-25 Rakesh Halder , Mahan Mj , Pranab Sardar

Let $G$ be a non-elementary word-hyperbolic group acting as a convergence group on a compact metrizable space $Z$ so that there exists a continuous $G$-equivariant map $i:\partial G\to Z$, which we call a \emph{Cannon-Thurston map}. We…

Group Theory · Mathematics 2016-03-02 Woojin Jeon , Ilya Kapovich , Christopher Leininger , Ken'ichi Ohshika

Given a tree of hyperbolic metric spaces $\pi:X\to T$ a la Bestvina--Feighn (\cite{BF}), and a hyperbolic subspace $Y$ of $X$ with an induced tree of hyperbolic spaces structure over a subtree $S\subset T$, we address the question as to…

Geometric Topology · Mathematics 2026-02-05 Rakesh Halder , Pranab Sardar

Baker and Riley proved that a free group of rank 3 can be contained in a hyperbolic group as a subgroup for which the Cannon-Thurston map is not well-defined. By using their result, we show that the phenomenon occurs for not only a free…

Group Theory · Mathematics 2012-06-27 Yoshifumi Matsuda , Shin-ichi Oguni

Given a hyperbolic subgroup $H$ of a hyperbolic group $G$ for which a Cannon-Thurston map $\hat i:\partial H \ra \partial G$ exists, we study the limit set $\Lambda_H$ of $H$ with respect to its action on $\partial G$. We prove that the set…

Geometric Topology · Mathematics 2013-08-23 Woojin Jeon , Ken'ichi Ohshika

We prove the existence of continuous boundary extensions (Cannon-Thurston maps) for the inclusion of a vertex space into a tree of (strongly) relatively hyperbolic spaces satisfying the qi-embedded condition. This implies the same result…

Group Theory · Mathematics 2011-03-24 Mahan Mj , Abhijit Pal

We prove the existence of Cannon-Thurston maps for Kleinian groups corresponding to pared manifolds whose boundary is incompressible away from cusps. We also describe the structure of these maps in terms of ending laminations.

Geometric Topology · Mathematics 2016-12-30 Shubhabrata Das , Mahan Mj

This is an announcement of some of the results obtained as a part of the second author's Ph.D. thesis. In the first part, we prove that the fundamental group of an acylindrical complex of hyperbolic groups with finite edge groups is…

Group Theory · Mathematics 2021-07-13 Pranab Sardar , Ravi Tomar

In this paper we will modify the Milnor--Thurston map, which maps a one dimensional mapping to a piece-wise linear of the same entropy, and study its properties. This will allow us to give a simple proof of monotonicity of topological…

Dynamical Systems · Mathematics 2019-01-23 Oleg Kozlovski

This paper gives a detailed analysis of the Cannon--Thurston maps associated to a general class of hyperbolic free group extensions. Let $F_N$ denote a free groups of finite rank $N\ge 3$ and consider a \emph{convex cocompact} subgroup…

Group Theory · Mathematics 2015-12-15 Spencer Dowdall , Ilya Kapovich , Samuel J. Taylor

Let $1\to (K,K_1)\to (G,N_G(K_1))\to(Q,Q_1)\to 1$ be a short exact sequence of pairs of finitely generated groups with $K$ strongly hyperbolic relative to proper subgroup $K_1$. Assuming that for all $g\in G$ there exists $k\in K$ such that…

Group Theory · Mathematics 2008-07-22 Abhijit Pal

Let $Y\to X$ be a proper map between proper hyperbolic metric spaces. A Cannon--Thurston map is a continuous extension $\partial Y \to \partial X$. We prove that in most known settings in which a Cannon--Thurston map exists it is uniformly…

Geometric Topology · Mathematics 2026-03-25 Indranil Bhattacharyya , Rakesh Halder , Nir Lazarovich , Mahan Mj

Let (X,d) be a tree (T) of hyperbolic metric spaces satisfying the quasi-isometrically embedded condition. Let $v$ be a vertex of $T$. Let $({X_v},d_v)$ denote the hyperbolic metric space corresponding to $v$. Then $i : X_v \rightarrow X$…

Geometric Topology · Mathematics 2011-03-24 Mahan Mitra

In this note we discuss the behavior of the Gromov boundaries and limit sets for the surface subgroups of the mapping class group with accidental parabolics constructed by the author and A. Reid in earlier work. Specifically, we show that…

Geometric Topology · Mathematics 2007-05-23 Christopher J. Leininger

Let N^h be a hyperbolic 3-manifold of bounded geometry corresponding to a hyperbolic structure on a pared manifold (M,P). Further, suppose that (\partial{M} - P) is incompressible, i.e. the boundary of M is incompressible away from cusps.…

Geometric Topology · Mathematics 2014-11-11 Mahan Mj

A typical question addressed in this paper is the following. Suppose $Z\subset Y\subset X$ are hyperbolic spaces where $Z$ is quasiconvex in both $Y$ and $X$. Let $\HAT{Y}$ and $\HAT{X}$ denote the spaces obtained from $Y$ and $X$…

Group Theory · Mathematics 2023-08-23 Pranab Sardar , Ravi Tomar
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