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arXiv · 2211.05298

On the structure of relatively biexact group von Neumann algebras

Changying Ding·Srivatsav Kunnawalkam Elayavalli
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Abstract

Using computations in the bidual of $\mathbb{B}(L^2M)$ we develop a new technique at the von Neumann algebra level to upgrade relative proper proximality to full proper proximality. This is used to structurally classify subalgebras of $L\Gamma$ where $\Gamma$ is an infinite group that is biexact relative to a finite family of subgroups $\{\Lambda_i\}_{i\in I}$ such that each $\Lambda_i$ is almost malnormal in $\Gamma$. This generalizes the result of \cite{DKEP21} which classifies subalgebras of von Neumann algebras of biexact groups. By developing a combination with techniques from Popa's deformation-rigidity theory we obtain a new structural absorption theorem for free products and a generalized Kurosh type theorem in the setting of properly proximal von Neumann algebras.

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Changying Ding, Srivatsav Kunnawalkam Elayavalli. 2022-11-10. On the structure of relatively biexact group von Neumann algebras. https://arxiv.org/abs/2211.05298

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