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A major direction in the theory of cluster algebras is to construct (quantum) cluster algebra structures on the (quantized) coordinate rings of various families of varieties arising in Lie theory. We prove that all algebras in a very large…

Quantum Algebra · Mathematics 2015-08-14 K. R. Goodearl , M. T. Yakimov

The theory of exact C*-algebras was introduced by Kirchberg and has been influential in recent development of C*-algebras. A fundamental result on exact C*-algebras is a local characterization of exactness. The notion of weakly exact von…

Operator Algebras · Mathematics 2007-05-23 Narutaka Ozawa

We prove that a compact quantum group is coamenable if and only if its corepresentation ring is amenable. We further propose a Foelner condition for compact quantum groups and prove it to be equivalent to coamenability. Using this Foelner…

Operator Algebras · Mathematics 2008-11-27 David Kyed

Suppose G is a compact Lie group and N is a closed normal subgroup of G acting freely on a smooth manifold X. The Cartan theorem alluded to in the title postulates the existence of a natural isomorphism between the G-equivariant cohomology…

Differential Geometry · Mathematics 2016-09-07 Liviu I. Nicolaescu

In this paper we consider the structure of general quantum W-algebras. We introduce the notions of deformability, positive-definiteness, and reductivity of a W-algebra. We show that one can associate a reductive finite Lie algebra to each…

High Energy Physics - Theory · Physics 2009-10-22 P. Bowcock , G Watts

We prove that the $L^1$-algebra of any non-Kac type compact quantum group does not satisfy operator biflatness. Since operator amenability implies operator biflatness, this result shows that any co-amenable, non-Kac type compact quantum…

Operator Algebras · Mathematics 2013-04-09 Martijn Caspers , Hun Hee Lee , Éric Ricard

We discuss some of the issues to be addressed in arriving at a definitive noncommutative Riemannian geometry that generalises conventional geometry both to the quantum domain and to the discrete domain. This also provides an introduction to…

Quantum Algebra · Mathematics 2009-10-31 S. Majid

Conformal inclusions of chiral conformal field theories, or more generally inclusions of quantum field theories, are described in the von Neumann algebraic setting by nets of subfactors, possibly with infinite Jones index if one takes…

Operator Algebras · Mathematics 2022-11-01 Marcel Bischoff , Simone Del Vecchio , Luca Giorgetti

We show that in order to prove that every second countable locally compact groups with exact reduced group C*-algebra is exact in the dynamical sense (i.e. KW-exact) it suffices to show this for totally disconnected groups.

Group Theory · Mathematics 2018-03-20 Chris Cave , Joachim Zacharias

We investigate a construction which associates a finite von Neumann algebra $M(\Gamma,\mu)$ to a finite weighted graph $(\Gamma,\mu)$. Pleasantly, but not surprisingly, the von Neumann algebra associated to to a `flower with $n$ petals' is…

Operator Algebras · Mathematics 2011-02-23 Madhushree Basu , Vijay Kodiyalam , V. S. Sunder

For any given algebra of local observables in Minkowski space an associated scaling algebra is constructed on which renormalization group (scaling) transformations act in a canonical manner. The method can be carried over to arbitrary…

High Energy Physics - Theory · Physics 2015-06-26 Detlev Buchholz , Rainer Verch

We define an integer-valued invariant of special cube complexes called the genus, and prove that having genus one characterizes special cube complexes with abelian fundamental group. Using the genus, we obtain a new proof that the…

Geometric Topology · Mathematics 2016-12-30 Corey Bregman

The Stone-von Neumann Theorem is a fundamental result which unified the competing quantum mechanical models of matrix mechanics and wave mechanics. It's mechanism of proof ultimately involved the study of unitary group representations on a…

Operator Algebras · Mathematics 2024-11-19 Lucas Hall , Leonard Huang , Jacek Krajczok , Mariusz Tobolski

The notion of simple compact quantum group is introduced. As non-trivial (noncommutative and noncocommutative) examples, the following families of compact quantum groups are shown to be simple: (a) The universal quantum groups $B_u(Q)$ for…

Quantum Algebra · Mathematics 2010-03-17 Shuzhou Wang

These are notes on seminal work of Freed, and subsequent developments, on the curvature properties of (Sobolev Lie) groups of maps from a Riemannian manifold into a compact Lie group. We are mainly interested in critical cases which are…

Differential Geometry · Mathematics 2020-02-26 Andres Larrain-Hubach , Doug Pickrell

For any right-angled Artin group, we show that its outer automorphism group contains either a finite-index nilpotent subgroup or a nonabelian free subgroup. This is a weak Tits alternative theorem. We find a criterion on the defining graph…

Group Theory · Mathematics 2009-10-27 Matthew B. Day

According to J. Feldman and C. Moore's well-known theorem on Cartan subalgebras, a variant of the group measure space construction gives an equivalence of categories between twisted countable standard measured equivalence relations and…

Operator Algebras · Mathematics 2008-03-18 Jean Renault

We investigate the structure of crossed product von Neumann algebras arising from Bogoljubov actions of countable groups on Shlyakhtenko's free Araki-Woods factors. Among other results, we settle the questions of factoriality and Connes'…

Operator Algebras · Mathematics 2025-07-17 Cyril Houdayer , Benjamin Trom

A conjecture of Hirschowitz's predicts that a globally generated vector bundle $W$ on a compact complex manifold $A$ satisfies the formal principle, i.e., the formal neighborhood of its zero section determines the germ of neighborhoods in…

Algebraic Geometry · Mathematics 2019-03-25 Jun-Muk Hwang

The purpose of this paper is to investigate the structure of Shlyakhtenko's free Araki-Woods factors using the framework of ultraproduct von Neumann algebras. We first prove that all the free Araki-Woods factors $\Gamma(H_{\mathbb R},…

Operator Algebras · Mathematics 2025-07-17 Cyril Houdayer , Sven Raum