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We prove an algebraic ``no-go theorem'' to the effect that a nontrivial Poisson algebra cannot be realized as an associative algebra with the commutator bracket. Using this, we show that there is an obstruction to quantizing the Poisson…

Mathematical Physics · Physics 2007-05-23 Mark J. Gotay , Janusz Grabowski

A group is boundedly acyclic if its bounded cohomology with trivial real coefficients vanishes in all positive degrees. Amenable groups are boundedly acyclic, while the first non-amenable examples were the group of compactly supported…

Group Theory · Mathematics 2022-06-14 Francesco Fournier-Facio , Clara Loeh , Marco Moraschini

The fundamental group of a hyperbolic manifold acts on the limit set, giving rise to a cross-product C^* algebra. We construct nontrivial K-cycles for the cross-product algebra, thereby extending some results of Connes and Sullivan to…

Differential Geometry · Mathematics 2007-05-23 John Lott

This paper consists of two parts. In the first part we show that any Poisson algebraic group over a field of characteristic zero and any Poisson Lie group admits a local quantization. This answers positively a question of Drinfeld. In the…

q-alg · Mathematics 2008-02-03 Pavel Etingof , David Kazhdan

We explore classifiability of crossed products of actions of countable amenable groups on compact, metrizable spaces. It is completely understood when such crossed products are simple, separable, unital, nuclear and satisfy the UCT: these…

Operator Algebras · Mathematics 2024-05-08 Eusebio Gardella , Shirly Geffen , Rafaela Gesing , Grigoris Kopsacheilis , Petr Naryshkin

Let $\gamma_{n}= O (\log^{-c}n)$ and let $\nu$ be the infinite product measure whose $n$-th marginal is Bernoulli$(1/2+\gamma_{n})$. We show that $c=1/2$ is the threshold, above which $\nu$-almost every point is simply Poisson generic in…

Dynamical Systems · Mathematics 2026-03-11 Michael Hochman , Nicolò Paviato

Poisson boundary is a measurable $\Gamma$-space canonically associated with a group $\Gamma$ and a probability measure $\mu$ on it. The collection of all measurable $\Gamma$-equivariant quotients, known as $\mu$-boundaries, of the Poisson…

Group Theory · Mathematics 2025-04-15 Samuel Dodds , Alex Furman

In this note we state a conjecture that characterizes unital C*-algebras for which the unitary group is amenable as a topological group in the norm topology. We prove the conjecture for simple, separable, stably finite, unital, $\mathcal…

Operator Algebras · Mathematics 2024-12-03 Vadim Alekseev , Max Schmidt , Andreas Thom

Amenable actions of locally compact groups on von Neumann algebras are investigated by exploiting the natural module structure of the crossed product over the Fourier algebra of the acting group. The resulting characterisation of…

Operator Algebras · Mathematics 2021-01-20 Andrew McKee , Reyhaneh Pourshahami

The purpose of the present paper is to establish explicit bounds on moderate deviation probabilities for a rather general class of geometric functionals enjoying the stabilization property, under Poisson input and the assumption of a…

Probability · Mathematics 2015-03-17 Peter Eichelsbacher , Martin Raic , Tomasz Schreiber

For each symmetric, aperiodic probability measure $\mu$ on a finitely generated group $G$, we define a subset $A_{\mu}$ consisting of group elements $g$ for which the limit of the ratio ${\mu^{\ast n}(g)}/{\mu^{\ast n}(e)}$ tends to $1$. We…

Group Theory · Mathematics 2017-12-21 Murray Elder , Cameron Rogers

We introduce and study a natural notion of selflessness for inclusions of C*-probability spaces, which in particular implies that all intermediate C*-algebras are selfless in the sense of Robert. We identify natural sources of selfless…

Operator Algebras · Mathematics 2025-12-04 Ben Hayes , Srivatsav Kunnawalkam Elayavalli , Gregory Patchell , Leonel Robert

The homotopy symmetric $C^*$-algebras are those separable $C^*$-algebras for which one can unsuspend in E-theory. We find a new simple condition that characterizes homotopy symmetric nuclear $C^*$-algebras and use it to show that the…

Operator Algebras · Mathematics 2016-03-07 Marius Dadarlat , Ulrich Pennig

The original definition of amenability given by von Neumann in the highly non-constructive terms of means was later recast by Day using approximately invariant probability measures. Moreover, as it was conjectured by Furstenberg and proved…

Functional Analysis · Mathematics 2020-05-29 Theo Bühler , Vadim A. Kaimanovich

In this paper I show that pointwise bounded asymptotic morphisms between separable metrisable locally convex *-algebras induce continuous maps between the quasi-unitary groups of the algebras, provided that the algebras support a certain…

Operator Algebras · Mathematics 2007-05-23 Edwin J. Beggs

In this work we introduce and study a new notion of amenability for actions of locally compact groups on $C^*$-algebras. Our definition extends the definition of amenability for actions of discrete groups due to Claire…

Operator Algebras · Mathematics 2022-05-04 Alcides Buss , Siegfried Echterhoff , Rufus Willett

A subgroup of an amenable group is amenable. The $C^*$-algebra version of this fact is false. This was first proved by M.-D. Choi who proved that the non-nuclear $C^*$-algebra $C^*_r(\ZZ_2*\ZZ_3)$ is a subalgebra of the nuclear Cuntz…

Operator Algebras · Mathematics 2013-02-26 Guyan Robertson , Tim Steger

A carefully motivated symmetric variant of the Poisson bracket in ordinary (not Grassmann) phase space variables is shown to satisfy identities which are in algebraic correspondence with the anticommutation postulates for quantized Fermion…

High Energy Physics - Theory · Physics 2007-05-23 S. K. Kauffmann

The main goal of this paper is to determine the Poisson boundary of lamplighter random walks over a general class of discrete groups $\Gamma$ endowed with a rich boundary. The starting point is the Strip Criterion of identification of the…

Probability · Mathematics 2010-02-26 Ecaterina Sava

We prove that any reduced twisted group C*-algebra of a selfless group with the rapid decay property is selfless. As an application, we show that twisted group C*-algebras of acylindrically hyperbolic groups (possibly with nontrivial finite…

Operator Algebras · Mathematics 2026-04-28 Sven Raum , Hannes Thiel , Eduard Vilalta