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In this note, we introduce and study a notion of bi-exactness for creation operators acting on full, symmetric and anti-symmetric Fock spaces. This is a generalization of our previous work, in which we studied the case of anti-symmetric…

Operator Algebras · Mathematics 2021-01-27 Kei Hasegawa , Yusuke Isono , Tomohiro Kanda

Let $a,b$ be elements in a unital C$^*$-algebra with $0\leq a,b\leq 1$. The element $a$ is absolutely compatible with $b$ if $$\vert a - b \vert + \vert 1 - a - b \vert = 1.$$ In this note we find some technical characterizations of…

Operator Algebras · Mathematics 2018-10-26 Nabin K. Jana , Anil K. Karn , Antonio M. Peralta

In this paper we introduce a family of examples that can be regarded as spaces of nonpositive curvature, but with the distinct quality that they are not complete as metric spaces. This amounts to the fact that they are modelled on a finite…

Metric Geometry · Mathematics 2009-08-27 Cristian Conde , Gabriel Larotonda

Interest in weak cubical n-categories arises in various contexts, in particular in topological field theories. In this paper, we describe a concept of double bicategory, namely a strict model of the theory of bicategories in Bicat. We show…

Category Theory · Mathematics 2010-01-15 Jeffrey C. Morton

We study group algebras for compact groups in the category of real and complex weakly complete vector spaces. We also show that the group algebra is a quotient of the weakly complete universal enveloping algebra of the Lie algebra of the…

Group Theory · Mathematics 2019-11-18 Karl Heinrich Hofmann , Linus Kramer

A notion of partial ideal for an operator algebra is a weakening the notion of ideal where the defining algebraic conditions are enforced only in the commutative subalgebras. We show that, in a von Neumann algebra, the ultraweakly closed…

Operator Algebras · Mathematics 2014-08-07 Nadish de Silva , Rui Soares Barbosa

We prove that for any group G in a fairly large class of generalized wreath product groups, the associated von Neumann algebra L(G) completely "remembers" the group G. More precisely, if L(G) is isomorphic to the von Neumann algebra…

Operator Algebras · Mathematics 2012-08-21 Adrian Ioana , Sorin Popa , Stefaan Vaes

We demonstrate a relative solidity property for the product of a nonamenable biexact group with an arbitrary infinite group in the measure equivalence setting. Among other applications, we obtain the following unique product decomposition…

Operator Algebras · Mathematics 2025-04-01 Changying Ding , Daniel Drimbe

This article is concerned with crossed products and their applications to random operators. We study the von Neumann algebra of a dynamical system using the underlying Hilbert algebra structure. This gives a particularly easy way to…

Mathematical Physics · Physics 2007-05-23 Daniel H. Lenz

We completely characterize when the algebra of an ample groupoid with coefficients in an arbitrary unital ring is von Neumann regular and, more generally, when the algebra of a graded ample groupoid is graded von Neumann regular. Our main…

Rings and Algebras · Mathematics 2025-05-13 Benjamin Steinberg , Daniel W. van Wyk

We generalize the notion of weakly mixing unitary representations to locally compact quantum groups, introducing suitable extensions of all standard characterizations of weak mixing to this setting. These results are used to complement the…

Operator Algebras · Mathematics 2017-07-11 Ami Viselter

This paper mainly concerns the von Neumann algebras induced by a tuple of multiplication operators on Bergman spaces which arise essentially from holomorphic proper maps over higher dimensional domains. We study the structures and abelian…

Operator Algebras · Mathematics 2016-08-23 Pan Ma , Hansong Huang

In the 1970s, Feldman and Moore classified separably acting von Neumann algebras containing Cartan MASAs using measured equivalence relations and 2-cocycles on such equivalence relations. In this paper, we give a new classification in terms…

Operator Algebras · Mathematics 2014-11-27 Allan P. Donsig , Adam H. Fuller , David R. Pitts

We study a relationship between the ultraproduct of a crossed product von Neumann algebra and the crossed product of an ultraproduct von Neumann algebra. As an application, the continuous core of an ultraproduct von Neumann algebra is…

Operator Algebras · Mathematics 2017-05-03 Reiji Tomatsu

The concept of biperfect (noncocommutative) weak Hopf algebras is introduced and their properties are discussed. A new type of quasi-bicrossed products are constructed by means of weak Hopf skew-pairs of the weak Hopf algebras which are…

Quantum Algebra · Mathematics 2009-11-10 Fang Li , Yao-Zhong Zhang

The notion of strong 1-boundedness for finite von Neumann algebras was introduced by Jung in arXiv:math/0510576 . This framework provided a free probabilistic approach to study rigidity properties and classification of finite von Neumann…

Operator Algebras · Mathematics 2021-10-26 Ben Hayes , David Jekel , Srivatsav Kunnawalkam Elayavalli

Making use of its smooth structure only, out of a connected oriented smooth $4$-manifold a von Neumann algebra is constructed. It is geometric in the sense that is generated by local operators and as a special four dimensional phenomenon it…

Mathematical Physics · Physics 2024-04-09 Gabor Etesi

We introduce a wide class of countable groups, called properly proximal, which contains all non-amenable bi-exact groups, all non-elementary convergence groups, and all lattices in non-compact semi-simple Lie groups, but excludes all inner…

Operator Algebras · Mathematics 2018-11-15 Rémi Boutonnet , Adrian Ioana , Jesse Peterson

We prove the dichotomy that every Coxeter group either has a strongly solid group von Neumann algebra or contains the product of an infinite cyclic group and a free group of rank 2. This generalizes the same dichotomy for right-angled…

Operator Algebras · Mathematics 2025-12-02 Martín Blufstein , Katherine Goldman , Koichi Oyakawa

We prove that the group-measure-space von Neumann algebra $L^\infty(T^2) \rtimes SL(2,Z)$ is solid. The proof uses topological amenability of the action of $SL(2,Z)$ on the Higson corona of $Z^2$.

Operator Algebras · Mathematics 2008-04-03 Narutaka Ozawa