Strongly singular MASA's and mixing actions in finite von Neumann algebras

Paul Jolissaint, Yves Stalder

Let $\Gamma$ be a countable group and let ${\Gamma }_0$ be an infinite abelian subgroup of $\Gamma$. We prove that if the pair $(\Gamma ,{\Gamma }_0)$ satisfies some combinatorial condition called (SS), then the…