English

Finiteness of Cannon--Thurston fibers

Geometric Topology 2026-03-25 v1 Group Theory

Abstract

Let YXY\to X be a proper map between proper hyperbolic metric spaces. A Cannon--Thurston map is a continuous extension YX\partial Y \to \partial X. We prove that in most known settings in which a Cannon--Thurston map exists it is uniformly finite-to-one. This answers a question due to Swarup from Bestvina's problem list and generalizes previous results of Cannon--Thurston, Kapovich--Lustig, Dowdall--Kapovich--Taylor and Ghosh.

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Cite

@article{arxiv.2603.22428,
  title  = {Finiteness of Cannon--Thurston fibers},
  author = {Indranil Bhattacharyya and Rakesh Halder and Nir Lazarovich and Mahan Mj},
  journal= {arXiv preprint arXiv:2603.22428},
  year   = {2026}
}

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