Fixed-point permanence under actions by finite quantum groups

Fuente: arXiv
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Auteur principal: Chirvasitu, Alexandru
Format: Preprint
Publié: 2025
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author Chirvasitu, Alexandru
author_facet Chirvasitu, Alexandru
contents Given an action by a finite quantum group $\mathbb{G}$ on a von Neumann algebra $M$, we prove that a number of familiar $W^*$ properties are equivalent for $M$ and the fixed-point algebra $M^{\mathbb{G}}$ (i.e. hold or not simultaneously for the two algebras); these include being hyperfinite, atomic, diffuse and of type $I$, $II$ or $III$. Moreover, in all cases the canonical central projections of $M$ and $M^{\mathbb{G}}$ cutting out the summand with the respective property coincide. The result generalizes its classical-$\mathbb{G}$ analogue due to Jones-Takesaki.
format Preprint
id arxiv_https___arxiv_org_abs_2504_14579
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Fixed-point permanence under actions by finite quantum groups
Chirvasitu, Alexandru
Operator Algebras
Functional Analysis
Quantum Algebra
20G42, 46L67, 46L10, 16W22, 46L52
Given an action by a finite quantum group $\mathbb{G}$ on a von Neumann algebra $M$, we prove that a number of familiar $W^*$ properties are equivalent for $M$ and the fixed-point algebra $M^{\mathbb{G}}$ (i.e. hold or not simultaneously for the two algebras); these include being hyperfinite, atomic, diffuse and of type $I$, $II$ or $III$. Moreover, in all cases the canonical central projections of $M$ and $M^{\mathbb{G}}$ cutting out the summand with the respective property coincide. The result generalizes its classical-$\mathbb{G}$ analogue due to Jones-Takesaki.
title Fixed-point permanence under actions by finite quantum groups
topic Operator Algebras
Functional Analysis
Quantum Algebra
20G42, 46L67, 46L10, 16W22, 46L52
url https://arxiv.org/abs/2504.14579