November 2023 Wreath-like products of groups and their von Neumann algebras I: W^∗-superrigidity
Ionuţ Chifan, Adrian Ioana, Denis Osin, Bin Sun
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Ann. of Math. (2) 198(3): 1261-1303 (November 2023). DOI: 10.4007/annals.2023.198.3.6
Abstract

We introduce a new class of groups called wreath-like products. These groups are close relatives of the classical wreath products and arise naturally in the context of group theoretic Dehn filling. Unlike ordinary wreath products, many wreath-like products have Kazhdan's property (T). In this paper, we prove that any group $G$ in a natural family of wreath-like products with property (T) is $\mathrm{W}^\ast$-superrigid: the group von Neumann algebra $\mathrm{L}(G)$ remembers the isomorphism class of $G$. This allows us to provide the first examples (in fact, $2^{\aleph_0}$ pairwise non-isomorphic examples) of $\mathrm{W}^\ast$-superrigid groups with property (T).

Copyright © 2023 Department of Mathematics, Princeton University
Ionuţ Chifan, Adrian Ioana, Denis Osin, and Bin Sun "Wreath-like products of groups and their von Neumann algebras I: W^∗-superrigidity," Annals of Mathematics 198(3), 1261-1303, (November 2023). https://doi.org/10.4007/annals.2023.198.3.6
Published: November 2023
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Vol.198 • No. 3 • November 2023
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