1,721,012 research outputs found
LOGIC FOR METRIC STRUCTURES AND THE NUMBER OF UNIVERSAL SOFIC AND HYPERLINEAR GROUPS
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Operator space and operator system analogs of Kirchberg's nuclear embedding theorem
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A VON NEUMANN ALGEBRA CHARACTERIZATION OF PROPERTY (T) FOR GROUPOIDS
Full text linkFor an arbitrary discrete probability-measure-preserving groupoid G, we provide a characterization of property (T) for G in terms of the groupoid von Neumann algebra L(G). More generally, we obtain a characterization of relative property (T) for a subgroupoid H⊂G in terms of the inclusions L(H)⊂L(G)
Actions on semigroups and an infinitary Gowers–Hales–Jewett Ramsey theorem
No full textWe introduce the notion of (Ramsey) action on a (filtered) semigroup. We then prove in this setting a general result providing a common generalization of the infinitary Gowers Ramsey theorem for multiple tetris operations, the infinitary Hales–Jewett theorems (for both located and nonlocated words), and the Farah–Hindman–McLeod Ramsey theorem for layered actions on partial semigroups. We also establish a polynomial version of our main result, recovering the polynomial Milliken–Taylor theorem of Bergelson–Hindman–Williams as a particular case. We present applications of our Ramsey-theoretic results to the structure of recurrence sets in amenable groups.</p
Fraïssé theory and the Poulsen simplex
Full text linkWe present a Fraïssé-theoretic perspective on the study of the Poulsen simplex and its properties
An intrinsic order-theoretic characterization of the weak expectation property
Full text linkWe prove the following characterization of the weak expectation property for operator systems in terms of Wittstock's matricial Riesz separation property: an operator system S satisfies the weak expectation property if and only if M_q(S) satisfies the matricial Riesz separation property for every q∈N. This can be seen as the noncommutative analog of the characterization of simplex spaces among function systems in terms of the classical Riesz separation property
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