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W$^*$-superrigidity for wreath products with groups having positive first $\ell^2$-Betti number (1403.7110v2)
Published 27 Mar 2014 in math.OA and math.GR
Abstract: In [BV12] we have proven that, for all hyperbolic groups and for all non-trivial free products $\Gamma$, the left-right wreath product group $G:=(Z/2Z){(\Gamma)} \rtimes (\Gamma \times \Gamma)$ is W$*$-superrigid. In this paper, we extend this result to other classes of countable groups. More precisely, we prove that for weakly amenable groups $\Gamma$ having positive first $\ell2$-Betti number, the same wreath product $G$ is W$*$-superrigid.