English

Fixed-point permanence under actions by finite quantum groups

Operator Algebras 2025-04-22 v1 Functional Analysis Quantum Algebra

Abstract

Given an action by a finite quantum group G\mathbb{G} on a von Neumann algebra MM, we prove that a number of familiar WW^* properties are equivalent for MM and the fixed-point algebra MGM^{\mathbb{G}} (i.e. hold or not simultaneously for the two algebras); these include being hyperfinite, atomic, diffuse and of type II, IIII or IIIIII. Moreover, in all cases the canonical central projections of MM and MGM^{\mathbb{G}} cutting out the summand with the respective property coincide. The result generalizes its classical-G\mathbb{G} analogue due to Jones-Takesaki.

Keywords

Cite

@article{arxiv.2504.14579,
  title  = {Fixed-point permanence under actions by finite quantum groups},
  author = {Alexandru Chirvasitu},
  journal= {arXiv preprint arXiv:2504.14579},
  year   = {2025}
}

Comments

7 pages + references

R2 v1 2026-06-28T23:04:41.691Z