Groups, Geometry, and Dynamics


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Volume 7, Issue 4, 2013, pp. 961–976
DOI: 10.4171/GGD/212

Published online: 2013-11-20

Hyperbolic hydra

Noel Brady[1], Will Dison[2] and Timothy R. Riley[3]

(1) University of Oklahoma, Norman, United States
(2) Bank of England, London, UK
(3) Cornell University, Ithaca, USA

We give examples of hyperbolic groups with finite rank free subgroups of huge (Ackermannian) distortion.

Keywords: Hyperbolic group, subgroup distortion, hydra, Ackermann's function

Brady Noel, Dison Will, Riley Timothy: Hyperbolic hydra. Groups Geom. Dyn. 7 (2013), 961-976. doi: 10.4171/GGD/212