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We study analogues of the radial subalgebras in free group factors (called the algebras of class functions) in the setting of compact quantum groups. For the free orthogonal quantum groups we show that they are not MASAs, as soon as we are…

Operator Algebras · Mathematics 2022-05-17 Jacek Krajczok , Mateusz Wasilewski

We define Ozawa's notion of bi-exactness to discrete quantum groups, and then prove some structural properties of associated von Neumann algebras. In particular, we prove that any non amenable subfactor of free quantum group von Neumann…

Operator Algebras · Mathematics 2013-08-26 Yusuke Isono

In this paper, we give examples of maximal amenable subalgebras of the free group factor of two generators. More precisely, we consider two copies of the hyperfinite factor $R_i$ of type $\mathrm{II}_1$. From each $R_i$, we take a Haar…

Operator Algebras · Mathematics 2016-10-03 Koichi Shimada

These notes provide an explanation of the type classification of von Neumann algebras, which has made many appearances in recent work on entanglement in quantum field theory and quantum gravity. The goal is to bridge a gap in the literature…

High Energy Physics - Theory · Physics 2025-09-30 Jonathan Sorce

We establish factoriality of $q$-Araki-Woods von Neumann algebras (with the number of generators at least two) in full generality, exploiting the approach via conjugate variables developed recently in the tracial case by Akihiro Miyagawa…

Operator Algebras · Mathematics 2023-06-28 Manish Kumar , Adam Skalski , Mateusz Wasilewski

The groups distinguish their von Neumann algebras, in the case when these are factors.

Operator Algebras · Mathematics 2015-05-21 Sa Ge Lee

In this paper we present a generalization of the Radon-Nikodym theorem proved by Pedersen and Takesaki. Given a normal, semifinite and faithful (n.s.f.) weight $\phi$ on a von Neumann algebra M and a strictly positive operator $\delta$,…

Operator Algebras · Mathematics 2007-05-23 Stefaan Vaes

It is proved that the $q$-Araki-Woods von Neumann algebras $\Gamma_q(\CH_\R,U_t)^{\prime\prime}$ for $q\in (-1,1)$ are factors if $dim(\CH_\R)\geq 3$.

Operator Algebras · Mathematics 2019-01-10 Panchugopal Bikram , Kunal Mukherjee

We give a short and simple proof, utilizing the pre-determinant of P. de la Harpe and G. Skandalis, that the universal covering group of the unitary group of a II$_1$ von Neumann algebra $\mathcal{M}$, when equipped with the norm topology,…

Operator Algebras · Mathematics 2024-12-17 Pawel Sarkowicz

We introduce the notion of L^2-rigidity for von Neumann algebras, a generalization of property (T) which can be viewed as an analogue for the vanishing of 1-cohomology into the left regular representation of a group. We show that…

Operator Algebras · Mathematics 2007-05-23 Jesse Peterson

In \cite{BAMU}, an ergodic theorem \`a la Birkhoff-von Neumann for the action of the fundamental group of a compact negatively curved manifold on the boundary of its universal cover is proved. A quick corollary is the irreducibility of the…

Group Theory · Mathematics 2016-01-06 Adrien Boyer , Antoine Pinochet Lobos

We construct a Fock space associated to a symmetric function $Q:U\times U \to (-1,1)$, where $U$ is a nonempty open subset of $\mathbb R^j$ for some $j$. Namely, we will have operator-valued distributions $a(x)$ and $a^+(y)$ satisfying…

Operator Algebras · Mathematics 2012-08-21 Adam Merberg

We introduce operator-valued twisted Araki-Woods algebras. These are operator-valued versions of a class of second quantization algebras that includes $q$-Gaussian and $q$-Araki-Woods algebras and also generalize Shlyakhtenko's von Neumann…

Operator Algebras · Mathematics 2024-07-30 Rahul Kumar R , Melchior Wirth

We prove that the approximately inner automorphism group of a separable strongly stable von Neumann algebra is contractible in the u-topology. Thus the automorphism group of the hyperfinite type III_1 factor is contractible.

Operator Algebras · Mathematics 2025-05-28 Narutaka Ozawa

The von Neumann algebra free product of arbitary finite dimensional von Neumann algebras with respect to arbitrary faithful states, at least one of which is not a trace, is found to be a type~III factor possibly direct sum a finite…

funct-an · Mathematics 2008-02-03 Kenneth J. Dykema

We show that for each (0<\lambda <1), the free Araki-Woods factor of type III(_{\lambda}) cannot be written as a tensor product of two diffuse von Neumann algebras (i.e., is prime), and does not contain a Cartan subalgebra.

Operator Algebras · Mathematics 2009-10-31 Dimitri Shlyakhtenko

We investigate Cartan subalgebras in nontracial amalgamated free product von Neumann algebras $M_1 \ast_B M_2$ over an amenable von Neumann subalgebra $B$. First, we settle the problem of the absence of Cartan subalgebra in arbitrary free…

Operator Algebras · Mathematics 2019-02-20 Rémi Boutonnet , Cyril Houdayer , Sven Raum

In this paper we introduce the concept of the upper free orbit-dimension of a finite von Neumann algebra, and we derive some of its basic properties. Using this concept, we are able to improve most of the applications of free entropy to…

Operator Algebras · Mathematics 2007-05-23 Don Hadwin , Junhao Shen

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

The aim of this paper is to introduce and study a large class of $\mathfrak{g}$-module algebras which we call factorizable by generalizing the Gauss factorization of (square or rectangular) matrices. This class includes coordinate algebras…

Representation Theory · Mathematics 2018-01-31 Arkady Berenstein , Karl Schmidt