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Boundary Dynamics, Cubical Actions, and Infinite Girth
Abstract
We develop two methods for proving infinite girth from boundary dynamics. First, we use topologically free extreme boundary actions to give a boundary-dynamical proof of infinite girth for finitely generated acylindrically hyperbolic groups. The second combines Nakamura's criterion with, respectively, flag-space and Roller-boundary dynamics, yielding infinite-girth results for semisimple S-algebraic groups and for essential non-elementary actions on finite-dimensional, second countable, non-Euclidean CAT(0) cube complexes. We also prove that every finitely generated large group has infinite girth, thereby answering a question of Akhmedov and Mishra.
Related
- Infinite girth and profinite properties of residually finite groups
- Random Quotients of Hyperbolic Spaces with Respect to WPD Actions and Linear Connectivity of the Boundary
- Fixed-point sets of semifree group actions on infinite-dimensional compact convex sets and their manifolds
- Simplicity and pure infiniteness for C*-algebras associated with stabilizers of boundary actions
- Hyperfiniteness of boundary actions via tree decompositions
BibTeX
@misc{amrutam2026boundary,
title = {{Boundary Dynamics, Cubical Actions, and Infinite Girth}},
author = {Tattwamasi Amrutam and Arka Banerjee and Daniel L. Gulbrandsen and Pratyush Mishra},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.31124},
eprint = {2608.31124},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.31124},
}
RIS
TY - UNPB
TI - Boundary Dynamics, Cubical Actions, and Infinite Girth
AU - Tattwamasi Amrutam
AU - Arka Banerjee
AU - Daniel L. Gulbrandsen
AU - Pratyush Mishra
PY - 2026
DA - 2026/08/31
PB - arXiv
DO - 10.48550/arxiv.2608.31124
UR - https://arxiv.org/abs/2608.31124
AB - We develop two methods for proving infinite girth from boundary dynamics. First, we use topologically free extreme boundary actions to give a boundary-dynamical proof of infinite girth for finitely generated acylindrically hyperbolic groups. The second combines Nakamura's criterion with, respectively, flag-space and Roller-boundary dynamics, yielding infinite-girth results for semisimple S-algebraic groups and for essential non-elementary actions on finite-dimensional, second countable, non-Euclidean CAT(0) cube complexes. We also prove that every finitely generated large group has infinite girth, thereby answering a question of Akhmedov and Mishra.
ER -