Local Hilbert--Schmidt stability

Fuente: arXiv
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Main Authors: Fournier-Facio, Francesco, Gerasimova, Maria, Spaas, Pieter
Format: Preprint
Published: 2023
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author Fournier-Facio, Francesco
Gerasimova, Maria
Spaas, Pieter
author_facet Fournier-Facio, Francesco
Gerasimova, Maria
Spaas, Pieter
contents We introduce a notion of local Hilbert--Schmidt stability, motivated by the recent definition by Bradford of local permutation stability, and give examples of (non-residually finite) groups that are locally Hilbert--Schmidt stable but not Hilbert--Schmidt stable. For amenable groups, we provide a criterion for local Hilbert--Schmidt stability in terms of group characters, by analogy with the character criterion of Hadwin and Shulman for Hilbert--Schmidt stable amenable groups. Furthermore, we study the (very) flexible analogues of local Hilbert--Schmidt stability, and we prove several results analogous to the classical setting. Finally, we prove that infinite sofic, respectively hyperlinear, property (T) groups are never locally permutation stable, respectively locally Hilbert--Schmidt stable. This strengthens the result of Becker and Lubotzky for classical stability, and answers a question of Lubotzky.
format Preprint
id arxiv_https___arxiv_org_abs_2307_13155
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Local Hilbert--Schmidt stability
Fournier-Facio, Francesco
Gerasimova, Maria
Spaas, Pieter
Group Theory
Operator Algebras
We introduce a notion of local Hilbert--Schmidt stability, motivated by the recent definition by Bradford of local permutation stability, and give examples of (non-residually finite) groups that are locally Hilbert--Schmidt stable but not Hilbert--Schmidt stable. For amenable groups, we provide a criterion for local Hilbert--Schmidt stability in terms of group characters, by analogy with the character criterion of Hadwin and Shulman for Hilbert--Schmidt stable amenable groups. Furthermore, we study the (very) flexible analogues of local Hilbert--Schmidt stability, and we prove several results analogous to the classical setting. Finally, we prove that infinite sofic, respectively hyperlinear, property (T) groups are never locally permutation stable, respectively locally Hilbert--Schmidt stable. This strengthens the result of Becker and Lubotzky for classical stability, and answers a question of Lubotzky.
title Local Hilbert--Schmidt stability
topic Group Theory
Operator Algebras
url https://arxiv.org/abs/2307.13155