An Operator-Valued Haagerup Inequality for Hyperbolic Groups

Fuente: arXiv
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Main Authors: Toyota, Ryo, Yang, Zhiyuan
Format: Preprint
Published: 2023
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author Toyota, Ryo
Yang, Zhiyuan
author_facet Toyota, Ryo
Yang, Zhiyuan
contents We study an operator-valued generalization of the Haagerup inequality for Gromov hyperbolic groups. In 1978, U. Haagerup showed that if $f$ is a function on the free group $\mathbb{F}_r$ which is supported on the $k$-sphere $S_k=\{x\in \mathbb{F}_r:\ell(x)=k\}$, then the operator norm of its left regular representation is bounded by $(k+1)\|f\|_2$. An operator-valued generalization of it was started by U. Haagerup and G. Pisier. One of the most complete form was given by A. Buchholz, where the $\ell^2$-norm in the original inequality was replaced by $k+1$ different matrix norms associated to word decompositions (this type of inequality is also called Khintchine-type inequality). We provide a generalization of Buchholz's result for hyperbolic groups.
format Preprint
id arxiv_https___arxiv_org_abs_2311_13651
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle An Operator-Valued Haagerup Inequality for Hyperbolic Groups
Toyota, Ryo
Yang, Zhiyuan
Operator Algebras
Functional Analysis
Group Theory
47
We study an operator-valued generalization of the Haagerup inequality for Gromov hyperbolic groups. In 1978, U. Haagerup showed that if $f$ is a function on the free group $\mathbb{F}_r$ which is supported on the $k$-sphere $S_k=\{x\in \mathbb{F}_r:\ell(x)=k\}$, then the operator norm of its left regular representation is bounded by $(k+1)\|f\|_2$. An operator-valued generalization of it was started by U. Haagerup and G. Pisier. One of the most complete form was given by A. Buchholz, where the $\ell^2$-norm in the original inequality was replaced by $k+1$ different matrix norms associated to word decompositions (this type of inequality is also called Khintchine-type inequality). We provide a generalization of Buchholz's result for hyperbolic groups.
title An Operator-Valued Haagerup Inequality for Hyperbolic Groups
topic Operator Algebras
Functional Analysis
Group Theory
47
url https://arxiv.org/abs/2311.13651