arXiv subjects

Takumi Nishihara

Publications and source records attributed to Takumi Nishihara.

2 recordsLinked to original sources

arXiv2026

Group actions on von Neumann algebras with compact open subgroups

We study strictly outer actions of locally compact groups with a compact open subgroup on von Neumann factors. For amenable groups, we prove 2-cohomology vanishing and obtain classification results using a description of the central sequence algebra and Rohlin-type observations. We also characterize the inclusions of factors associated with group actions, and extend M. Choda's result to this locally compact setting.

math.OA↗

arXiv2026

Compact group Rohlin actions and $G$-kernels on von Neumann algebras

We provide a new construction of a topological group model for the string group of a compact, simple, and simply-connected Lie group, by solving the obstruction realization problem for compact group $G$-kernels on full factors. Furthermore, we introduce the Rohlin property for actions and cocycle actions of compact groups in order to establish cohomology vanishing theorems.

math.OA↗