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We characterize supramenable groups in terms of existence of invariant probability measures for partial actions on compact Hausdorff spaces and existence of tracial states on partial crossed products. These characterizations show that, in…

Operator Algebras · Mathematics 2020-11-09 Eduardo P. Scarparo

In this article, we consider a twisted partial action $\alpha$ of a group $G$ on a ring $R$ and it is associated partial crossed product $R*_{\alpha}^wG$. We study necessary and sufficient conditions for the commutativity and simplicity of…

Rings and Algebras · Mathematics 2013-06-25 Alexandre Baraviera , Wagner Cortes , Marlon Soares

We consider a twisted action of a discrete group G on a unital C*-algebra A and give conditions ensuring that there is a bijective correspondence between the maximal invariant ideals of A and the maximal ideals in the associated reduced…

Operator Algebras · Mathematics 2023-07-19 Erik Bédos , Roberto Conti

In this paper, we construct large subalgebras of crossed product C*-algebras of noncommutative C*-dynamics from ideals. We apply our results to study locally trivial unital $C(X)$-algebras such as mapping tori.

Operator Algebras · Mathematics 2023-10-10 Xiaochun Fang , N. C. Phllips , Junqi Yang

Given a Hausdorff compact space X, we study the C^*-(semi)-norms on the algebraic tensor product $A\otimes_{alg,C(X)} B$ of two C(X)-algebras A and B over C(X). In particular, if one of the two C(X)-algebras defines a continuous field of…

Operator Algebras · Mathematics 2016-09-07 Etienne Blanchard

The C*-algebra of a skew-product topological graph is a crossed product of the C*-algebra of the base topological graph by a coaction.

Operator Algebras · Mathematics 2013-01-15 S. Kaliszewski , John Quigg

We establish $\mathcal{Z}$-stability for crossed products of outer actions of amenable groups on $\mathcal{Z}$-stable $C^*$-algebras under a mild technical assumption which we call McDuff property with respect to invariant traces. We obtain…

Operator Algebras · Mathematics 2022-09-29 Eusebio Gardella , Shirly Geffen , Petr Naryshkin , Andrea Vaccaro

We study some generalizations of the notion of regular crossed products K*G. For the case when K is an algebraically closed field, we give necessary and sufficient conditions for the twisted group ring K*G to be an n-weakly regular ring, a…

Representation Theory · Mathematics 2013-02-15 V. Bovdi , S. Mihovski

The author's recent results on spectral invariant dense subalgebras of C*-algebras associated with dynamical systems are summarized. If G is a compactly generated polynomial growth Type R Lie group, and the action of G on S(M) (Schwartz…

funct-an · Mathematics 2016-02-15 Larry B. Schweitzer

We consider tracial stability, which requires that tuples of elements of a C*-algebra with a trace that nearly satisfy the relation are close to tuples that actually satisfy the relation. Here both "near" and "close" are in terms of the…

Operator Algebras · Mathematics 2017-06-23 Don Hadwin , Tatiana Shulman

Given a minimal action $G\curvearrowright X$ of a countable group $G$ on a compact space $X$, we prove that if the reduced crossed product $G\ltimes_rC(X)$ is simple, then there exists a point whose stabilizer subgroup has trivial amenable…

Operator Algebras · Mathematics 2026-05-22 Yair Hartman , Mehrdad Kalantar

$HC_*(A \rtimes G)$ is the cyclic homology of the crossed product algebra $A \rtimes G.$ For any $g \epsilon G$ we will define a homomorphism from $HC_*^g(A),$ the twisted cylic homology of $A$ with respect to $g,$ to $HC_*(A \rtimes G).$…

K-Theory and Homology · Mathematics 2014-03-31 Jack M. Shapiro

The paper presents a construction of the crossed product of a C*-algebra by a commutative semigroup of bounded positive linear maps generated by partial isometries. In particular, it generalizes Antonevich, Bakhtin, Lebedev's crossed…

Operator Algebras · Mathematics 2014-10-10 B. K. Kwasniewski

This paper is one of a series whose goal is to stabilize the twisted Arthur-Selberg's trace formula. Here we define the objects appearing in the geometric side of the twisted trace formula. We define also the similar stable and endoscopic…

Representation Theory · Mathematics 2014-06-10 Colette Moeglin , Jean-Loup Waldspurger

Consider a smooth affine algebraic variety $X$ over an algebraically closed field, and let a finite group $G$ act on it. We assume that the characteristic of the field is greater than the dimension of $X$ and the order of $G$. An explicit…

Quantum Algebra · Mathematics 2007-05-23 Rina Anno

We define and systematically study nonassociative C*-algebras as C*-algebras internal to a topological tensor category. We also offer a concrete approach to these C*-algebras, as G-invariant, norm closed *-subalgebras of bounded operators…

Quantum Algebra · Mathematics 2011-02-04 P. Bouwknegt , K. Hannabuss , V. Mathai

To a continuous action of a vector group on a $C^*$-algebra, twisted by the imaginary exponential of a symplectic form, one associates a Rieffel deformed algebra as well as a twisted crossed product. We show that the second one is…

Operator Algebras · Mathematics 2014-06-30 I. Beltita , M. Mantoiu

The graph C*-algebra of a directed graph E is the universal C*-algebra generated by a family of partial isometries satisfying relations which reflect the path structure of E. In the first part of this paper we consider coverings of directed…

Operator Algebras · Mathematics 2007-05-23 Klaus Deicke , David Pask , Iain Raeburn

We survey the extensions of a group by a group using crossed products instead of exact sequences of groups. The approach has various advantages, one of them being that the crossed product is an universal object. Several new applications are…

Group Theory · Mathematics 2014-03-18 A. L. Agore , G. Militaru

We establish comparison and divisibility properties for crossed product C*-algebras arising from automorphisms of algebras C (X, D) which lie over minimal homeomorphisms, from actions of compact groups which have finite Rokhlin dimension…

Operator Algebras · Mathematics 2026-04-14 Dawn Archey , Julian Buck , Javad Mohammadkarimi , N. Christopher Phillips , Apurva Seth