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Main Authors: Deng, Jintao, Toyota, Ryo
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2503.04578
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author Deng, Jintao
Toyota, Ryo
author_facet Deng, Jintao
Toyota, Ryo
contents In this paper, we study the geometric property (T) for discretized warped cones of an action on a compact Lie group $M$ by its finitely generated subgroup. We show that if a subgroup $G$ is dense in $M$, then the associated discretized warped cone $\bigsqcup_n M\times \{t(n)\}$ does not have geometric property (T) for any sequence of positive numbers $\{t(n)\}_{n\in \mathbb{N}}$ converging to $\infty$. This result applies to certain ergodic actions of groups with property (T), for example, the action of $SO(d,\mathbb{Z}[\frac{1}{5}])$ on $SO(d)$ with $d\geq 5$. As an application, we obtain new examples of expanders without geometric property (T), including certain superexpanders.
format Preprint
id arxiv_https___arxiv_org_abs_2503_04578
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Non-geometric property (T) of warped cones
Deng, Jintao
Toyota, Ryo
Group Theory
Dynamical Systems
Operator Algebras
37A55
In this paper, we study the geometric property (T) for discretized warped cones of an action on a compact Lie group $M$ by its finitely generated subgroup. We show that if a subgroup $G$ is dense in $M$, then the associated discretized warped cone $\bigsqcup_n M\times \{t(n)\}$ does not have geometric property (T) for any sequence of positive numbers $\{t(n)\}_{n\in \mathbb{N}}$ converging to $\infty$. This result applies to certain ergodic actions of groups with property (T), for example, the action of $SO(d,\mathbb{Z}[\frac{1}{5}])$ on $SO(d)$ with $d\geq 5$. As an application, we obtain new examples of expanders without geometric property (T), including certain superexpanders.
title Non-geometric property (T) of warped cones
topic Group Theory
Dynamical Systems
Operator Algebras
37A55
url https://arxiv.org/abs/2503.04578