Hyperlinear and Sofic Groups: A Brief Guide


This is an introductory survey of the emerging theory of two new classes of (discrete, countable) groups, called hyperlinear and sofic groups. They can be characterized as subgroups of metric ultraproducts of families of, respectively, unitary groups U(n) and symmetric groups Sn, n ∈ N. Hyperlinear groups come from theory of operator algebras (Connes… (More)


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