Speaker: Kai Toyosawa (Univ. Münster)

Title: Relative biexactness of amalgamated free product von Neumann algebras

Time/Date: March 10 (Tue), 2026, 3:00-4:30pm

Room: 126 Math. Sci. Building (It will be also online. The Zoom link is the same as before. If you don't have one, please ask Kawahigashi.)

Abstract: The notion of biexact groups was introduced by Ozawa in his study of solidity for free group factors and was recently extended to general von Neumann algebras by Ding and Peterson. In this talk, I will show that the amalgamated free product of weakly exact von Neumann algebras over an injective subalgebra is relatively biexact, extending Ozawa's result for groups to the von Neumann algebra setting. The proof uses a universal property of Toeplitz-Pimsner algebras and a locally convex topology on bimodules that characterizes biexactness for von Neumann algebras. This is joint work with Zhiyuan Yang.