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We prove that if A and B are Fell bundles over the locally compact groups G and H respectively, then the minimal (maximal) tensor product of the C*-algebra of kernels of A with the C*-algebra of kernels of B agrees with the C*-algebra of…

Operator Algebras · Mathematics 2024-12-18 Fernando Abadie

We define weakly proper Fell bundles and construct exotic fixed point algebras for such bundles. Three alternative constructions of such algebras are given. Under a kind of freeness condition, one of our constructions implies that every…

Operator Algebras · Mathematics 2021-07-05 Damián Ferraro

We consider modules E over a C*-algebra A which are equipped with a map into A_+ that has the formal properties of a norm. We completely determine the structure of these modules. In particular, we show that if A has no nonzero commutative…

funct-an · Mathematics 2008-02-03 N. C. Phillips , N. Weaver

For a Fell bundle $\mathcal{B}=\left\{B_{s}\right\}_{s \in G}$ over a discrete group $G$, we use representations theory of $\mathcal{B}$ to construct the Fourier and Fourier-Stieltjes spaces $A(\mathcal{B})$ and $B(\mathcal{B})$ of…

Operator Algebras · Mathematics 2022-04-20 Massoud Amini , Mohammad Reza Ghanei

Continuous actions of topological groups on compact Hausdorff spaces $X$ are investigated which induce almost periodic functions in the corresponding commutative C*-algebra. The unique invariant mean on the group resulting from averaging…

Operator Algebras · Mathematics 2009-03-11 M. Frank , V. Manuilov , E. Troitsky

In this paper we construct the notions of double Fell bundle and double C*-category for possible future use as tools to describe noncommutative spaces, in particular in finite dimensions. We identify the algebra of sections of a double Fell…

Mathematical Physics · Physics 2013-04-18 Rachel A. D. Martins

We introduce a natural concept of positive definiteness for bundle maps between Fell bundles over (possibly different) discrete groups and describe several examples. Such maps induce completely positive maps between the associated full…

Operator Algebras · Mathematics 2025-07-03 Erik Bédos , Roberto Conti

In this paper, we show that if E is a Fell bundle over an amenable \'etale locally compact Hausdorff groupoid such that every fiber on the unit space is nuclear, then $C?^*r(E)$ is also nuclear. In order to show this result, we introduce…

Operator Algebras · Mathematics 2013-01-30 Takuya Takeishi

We study two classes of operator algebras associated with a unital subsemigroup $P$ of a discrete group $G$: one related to universal structures, and one related to co-universal structures. First we provide connections between universal…

Operator Algebras · Mathematics 2022-03-09 Evgenios T. A. Kakariadis , Elias G. Katsoulis , Marcelo Laca , Xin Li

We consider a class of proper actions of locally compact groups on imprimitivity bimodules over C*-algebras which behave like the proper actions on C*-algebras introduced by Rieffel in 1988. We prove that every such action gives rise to a…

Operator Algebras · Mathematics 2007-05-23 Astrid an Huef , Iain Raeburn , Dana P. Williams

In this paper we give a simple proof of the maximality of dual coactions on full cross-sectional C*-algebras of Fell bundles over locally compact groups. As applications we extend certain exotic crossed-product functors in the sense of…

Operator Algebras · Mathematics 2015-07-22 Alcides Buss , Siegfried Echterhoff

We define the notion of a $\Lambda$-system of $C^*$-correspondences associated to a higher-rank graph $\Lambda$. Roughly speaking, such a system assigns to each vertex of $\Lambda$ a $C^*$-algebra, and to each path in $\Lambda$ a…

Operator Algebras · Mathematics 2009-02-17 Valentin Deaconu , Alex Kumjian , David Pask , Aidan Sims

We prove that the reduced cross-sectional algebra of a Fell bundle with the approximation property over an inverse semigroup is exact if and only if the unit fiber of the Fell bundle is exact. This generalizes a recent result of the…

Operator Algebras · Mathematics 2026-05-21 Changyuan Gao , Julian Kranz

We study the groupoid C*-algebras associated to the equivalence relation induced by a quotient map on a locally compact Hausdorff space. This C*-algebra is always a Fell algebra, and if the quotient space is Hausdorff, it is a…

Operator Algebras · Mathematics 2012-07-12 Lisa Orloff Clark , Astrid an Huef , Iain Raeburn

We define partial product systems over N. They generalise product systems over N and Fell bundles over Z. We define Toeplitz C*-algebras and relative Cuntz-Pimsner algebras for them and show that the section C*-algebra of a Fell bundle over…

Operator Algebras · Mathematics 2019-12-23 Devarshi Mukherjee , Ralf Meyer

We describe the $C^*$-algebra of an $E$-unitary or strongly 0-$E$-unitary inverse semigroup as the partial crossed product of a commutative $C^*$-algebra by the maximal group image of the inverse semigroup. We give a similar result for the…

Operator Algebras · Mathematics 2015-12-08 David Milan , Benjamin Steinberg

To every Fell bundle $\mathscr C$ over a locally compact group ${\sf G}$ one associates a Banach $^*$-algebra $L^1({\sf G}\,\vert\,\mathscr C)$. We prove that it is symmetric whenever ${\sf G}$ with the discrete topology is rigidly…

Operator Algebras · Mathematics 2024-04-04 Felipe Flores , Diego Jauré , Marius Mantoiu

We prove that the Cuntz-Pimsner algebra O(E) of a vector bundle E over a compact metrizable space X is determined up to an isomorphism of C(X)-algebras by the ideal (1-[E])K(X) of the K-theory ring K(X). Moreover, if E and F are vector…

Operator Algebras · Mathematics 2010-04-27 Marius Dadarlat

We prove a version of Wordingham's theorem for left regular representations in the setting of Fell bundles of inverse semigroups and use this result to discuss the various associated cross sectional C*-algebras.

Operator Algebras · Mathematics 2016-11-11 Erik Bédos , Magnus D. Norling

A method for deforming C*-algebras is introduced, which applies to C*-algebras that can be described as the cross-sectional C*-algebra of a Fell bundle. Several well known examples of non-commutative algebras, usually obtained by deforming…

funct-an · Mathematics 2008-02-03 Beatriz Abadie , Ruy Exel