English

Examples of compact quantum groups with $\operatorname{\mathsf{L}^{\!\infty}}(\mathbb{G})$ a factor

Operator Algebras 2024-09-05 v4 Functional Analysis

Abstract

For each λ]0,1]\lambda\in\left]0,1\right] we exhibit an uncountable family of compact quantum groups G\mathbb{G} such that the von Neumann algebra L ⁣(G)\mathsf{L}^{\!\infty}(\mathbb{G}) is the injective factor of type IIIλ\mathrm{III}_\lambda with separable predual. We also show that uncountably many injective factors of type III0\mathrm{III}_0 arise as L ⁣(G)\mathsf{L}^{\!\infty}(\mathbb{G}) for some compact quantum group G\mathbb{G}. To distinguish between our examples we introduce invariants related to the scaling group modeled on the Connes invariant TT for von Neumann algebras and investigate the connection between so obtained invariants of G\mathbb{G} and the Connes invariants T(L ⁣(G))T(\mathsf{L}^{\!\infty}(\mathbb{G})), S(L ⁣(G))S(\mathsf{L}^{\!\infty}(\mathbb{G})). In the final section we show that factors of type I\mathrm{I} cannot be obtained as L ⁣(G)\mathsf{L}^{\!\infty}(\mathbb{G}) for a non-trivial compact quantum group G\mathbb{G}.

Keywords

Cite

@article{arxiv.2203.10976,
  title  = {Examples of compact quantum groups with $\operatorname{\mathsf{L}^{\!\infty}}(\mathbb{G})$ a factor},
  author = {Jacek Krajczok and Piotr M. Sołtan},
  journal= {arXiv preprint arXiv:2203.10976},
  year   = {2024}
}

Comments

Acknowledgments updated

R2 v1 2026-06-24T10:20:30.249Z