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We show that if $\AA$ is a Fell bundle over a locally compact group $G$, then there is a natural coaction $\delta$ of $G$ on the Fell-bundle $C^*$-algebra $C^*(G,\AA)$ such that if $\hat{\delta}$ is the dual action of $G$ on the crossed…

Operator Algebras · Mathematics 2009-09-18 S. Kaliszewski , Paul S. Muhly , John Quigg , Dana P. Williams

This article extends the main results of the publication arXiv:2001.01312 to the case of a twisted groupoid. More precisely, it gives a decomposition of the C*-algebra of a twisted locally compact groupoid with Haar system in presence of a…

Operator Algebras · Mathematics 2021-03-22 Jean Renault

Starting from an arbitrary endomorphism \alpha of a unital C*-algebra A we construct a crossed product. It is shown that the natural construction depends not only on the C*-dynamical system (A,\alpha) but also on the choice of an ideal…

Operator Algebras · Mathematics 2014-12-31 B. K. Kwasniewski , A. V. Lebedev

We introduce and investigate some examples of C$^*$-algebras which are related to multiplication maps in the ring of $p$-adic integers. We find ideals within these algebras and use the corresponding short exact sequences to compute the…

Operator Algebras · Mathematics 2023-12-18 Shelley Hebert , Slawomir Klimek , Matt McBride , J. Wilson Peoples

Given a C*-dynamical system (A,G,\alpha), we discuss conditions under which subalgebras of the multiplier algebra M(A) consisting of fixed points for \alpha are Morita-Rieffel equivalent to ideals in the crossed product of A by G. In case G…

Operator Algebras · Mathematics 2007-05-23 Ruy Exel

Let $\G$ be a locally compact group satisfying some technical requirements and $\wG$ its unitary dual. Using the theory of twisted crossed product $C^*$-algebras, we develop a twisted global quantization for symbols defined on $\G\times\wG$…

Functional Analysis · Mathematics 2016-05-18 H. Bustos , M. Mantoiu

The crossed products of locally C*-algebras are defined and a Takai duality theorem for inverse limit actions of a locally compact group on a locally C*-algebra is proved.

Operator Algebras · Mathematics 2007-05-23 Maria Joita

For a quasitriangular C*-quantum group, we enrich the twisted tensor product constructed in the first part of this series to a monoidal structure on the category of its continuous coactions on C*-algebras. We define braided C*-quantum…

Operator Algebras · Mathematics 2024-06-25 Ralf Meyer , Sutanu Roy , Stanisław Lech Woronowicz

In this paper, we prove a Galois correspondence for compact group actions on C*-algebras in the presence of a commuting minimal action. Namely, we show that there is a one to one correspondence between the C*-subalgebras that are globally…

Operator Algebras · Mathematics 2019-04-30 Costel Peligrad

We characterize the ideals of the semicrossed product $C_0(X) \times_\phi \mathbb{Z}_+$ with left (resp. right) approximate unit.

Operator Algebras · Mathematics 2023-01-12 Charalampos Magiatis

Some well known results by Haagerup, Jolissaint and de la Harpe may be extended to the setting of a reduced crossed product of a C*-algebra A by a discrete group $G.$ We show that for many discrete groups, which include Gromov's hyperbolic…

Operator Algebras · Mathematics 2021-02-08 Erik Christensen

We study the relationship between the ultraproduct of a crossed product C*algebra $(A\rtimes_{r}G)^{\omega}$ and the crossed product of an ultraproduct C*algebra $A^{\omega}\rtimes _{r}G$ for a fixed free ultrafilter $\omega$ on…

Operator Algebras · Mathematics 2026-02-24 Zhengyu Fu

Given an action $G \curvearrowright X$ of a discrete and countable infinite group $G$ on a compact and Hausdorff space $X$, we regard $\ell^1(G\curvearrowright X)$ as the Banach *-algebra crossed product associated to the action. We…

Functional Analysis · Mathematics 2026-03-19 Tabaré Roland

In this paper, we consider both algebraic crossed products of commutative complex algebras A with the integers under an automorphism of A, and Banach algebra crossed products of commutative C^*-algebras A with the integers under an…

Operator Algebras · Mathematics 2023-05-31 Christian Svensson , Sergei Silvestrov , Marcel de Jeu

We study the ideal structure of reduced crossed product of topological dynamical systems of a countable discrete group. More concretely, for a compact Hausdorff space $X$ with an action of a countable discrete group $\Gamma$, we consider…

Operator Algebras · Mathematics 2017-01-13 Takuya Kawabe

Given a unital $C(X)$-algebra $A$ discrete group $\Gamma$ and an action $\alpha: \Gamma\to \text{aut}(A)$ which leaves $C(X)$ invariant and such that $C(X)\rtimes_{\alpha,r} \Gamma$ is simple, and a $2$-cocycle $\omega$, we obtain a…

Operator Algebras · Mathematics 2024-04-10 Tattwamasi Amrutam , Ilan Hirshberg , Apurva Seth

We consider Deaconu--Renault groupoids associated to actions of finite-rank free abelian monoids by local homeomorphisms of locally compact Hausdorff spaces. We study simplicity of the twisted C*-algebra of such a groupoid determined by a…

Operator Algebras · Mathematics 2024-05-10 Becky Armstrong , Nathan Brownlowe , Aidan Sims

We introduce the notion of strong Morita equivalence for group actions on locally C*-algebras and prove that the crossed products associated with two strongly Morita equivalent continuous inverse limit actions of a locally compact group G…

Operator Algebras · Mathematics 2007-10-02 Maria Joita

We construct the crossed product of a C(X)-algebra by an endomorphism, in such a way that the endomorphism itself becomes induced by the bimodule of continuous sections of a vector bundle. Some motivating examples for such a construction…

Operator Algebras · Mathematics 2011-11-21 Ezio Vasselli

We extend the theory of Fourier--Stieltjes algebras to the category of twisted actions by \'etale groupoids on arbitrary C*-bundles, generalizing theories constructed previously by B\'{e}dos and Conti for twisted group actions on unital…

Operator Algebras · Mathematics 2025-11-18 Alcides Buss , Bartosz Kwaśniewski , Andrew McKee , Adam Skalski