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We give a definition of an amenable fusion module over a fusion algebra. A notion of relative integrability for the `coduals' of coideals of compact quantum groups was recently introduced in the joint work of de Commer and Dzokou Talla. We…

Quantum Algebra · Mathematics 2023-11-21 Benjamin Anderson-Sackaney , Leonid Vainerman

We analyze the dichotomy amenable/paradoxical in the context of (discrete, countable, unital) semigroups and corresponding semigroup rings. We consider also F{\o}lner's type characterizations of amenability and give an example of a…

Operator Algebras · Mathematics 2022-07-11 Pere Ara , Fernando Lledó , Diego Martínez

In this paper, we introduce actions of fusion algebras on unital $C^*$-algebras, and define amenability for fusion algebraic actions. Motivated by S.\ Neshveyev et al.'s work, considering the co-representation ring of a compact quantum…

Operator Algebras · Mathematics 2021-08-24 Xiao Chen , Debashish Goswami , Huichi Huang

We introduce and study several amenability properties for unitary corepresentations and *-representations of algebraic quantum groups, which may be used to characterize amenability or co-amenability of such groups. As a background for this…

Operator Algebras · Mathematics 2007-05-23 E. Bedos , R. Conti , L. Tuset

We establish several new characterizations of amenable $W^*$- and $C^*$-dynamical systems over arbitrary locally compact groups. In the $W^*$-setting we show that amenability is equivalent to (1) a Reiter property and (2) the existence of a…

Operator Algebras · Mathematics 2020-08-25 Alex Bearden , Jason Crann

We define concepts of amenability and co-amenability for algebraic quantum groups in the sense of A. Van Daele. We show that co-amenability of an algebraic quantum group always implies amenability of its dual. Various necessary and/or…

Operator Algebras · Mathematics 2007-05-23 E. Bedos , G. J. Murphy , L. Tuset

We give the first examples of (non-amenable group) amenable actions on stably finite simple C*-algebras. More precisely, we give such actions for any countable group in an explicit way. The main ingredients of our construction are the full…

Operator Algebras · Mathematics 2026-02-09 Yuhei Suzuki

We define possibly unsaturated, upper semicontinuous Fell bundles over Hausdorff, locally compact groupoids and establish a universal property for representations of their full section C*-algebras on Hilbert modules over arbitrary…

Operator Algebras · Mathematics 2026-04-07 Alcides Buss , Rohit Holkar , Ralf Meyer

In the present article we review an approximation procedure for amenable traces on unital and separable C*-algebras acting on a Hilbert space in terms of F\o lner sequences of non-zero finite rank projections. We apply this method to…

Operator Algebras · Mathematics 2013-10-17 Pere Ara , Fernando Lledó

We study the C*-algebras of Fell bundles. In particular, we prove the analogue of Renault's disintegration theorem for groupoids. As in the groupoid case, this result is the key step in proving a deep equivalence theorem for the C*-algebras…

Operator Algebras · Mathematics 2008-08-18 Paul S. Muhly , Dana P. Williams

We continue the investigation of notions of approximate amenability that were introduced in work of the second and third authors. It is shown that every boundedly approximately contractible Banach algebra has a bounded approximate identity.…

Functional Analysis · Mathematics 2009-03-26 Y. Choi , F. Ghahramani , Y. Zhang

Amenability for groups can be extended to metric spaces, algebras over commutative fields and $C^*$-algebras by adapting the notion of F{\o}lner nets. In the present article we investigate the close ties among these extensions and show that…

Operator Algebras · Mathematics 2018-08-08 Pere Ara , Kang Li , Fernando Lledó , Jianchao Wu

In the present paper, the concepts of module (uniform) approximate amenability and contractibility of Banach algebras that are modules over another Banach algebra, are introduced. The general theory is developed and some hereditary…

Functional Analysis · Mathematics 2013-01-16 Hasan Pourmahmood-Aghababa , Abasalt Bodaghi

We develop the notion of Rokhlin dimension for partial actions of finite groups, extending the well-established theory for global systems. The partial setting exhibits phenomena that cannot be expected for global actions, usually stemming…

Operator Algebras · Mathematics 2022-01-25 Fernando Abadie , Eusebio Gardella , Shirly Geffen

Let $\mathfrak{A}$ be a Banach algebra, and $\mathcal{X}$ a Banach $\mathfrak{A}$-bimodule. A bounded linear mapping $\mathcal{D}:\mathfrak{A}\rightarrow \mathcal{X}$ is approximately semi-inner derivation if there eixist nets…

Functional Analysis · Mathematics 2019-10-22 M. Shams Kojanaghi , K. Haghnejad Azar , M. R. Mardanbeigi

We generalize the main result of Kamalov and show that if $G$ is an amenable discrete group with an action $\alpha$ on a finite nuclear unital $C^*$-algebra $A$ such that the reduced crossed product $A\rtimes_{\alpha,r} G$ has property $T$,…

Operator Algebras · Mathematics 2016-09-14 Baojie Jiang , Chi-Keung Ng

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

Let $\mathbb{G}$ be a compact quantum group and $A\subseteq B$ an inclusion of $\sigma$-finite $\mathbb{G}$-dynamical von Neumann algebras. We prove that the $\mathbb{G}$-inclusion $A\subseteq B$ is strongly equivariantly amenable if and…

Operator Algebras · Mathematics 2025-04-10 K. De Commer , J. De Ro

We show that an \'etale groupoid which is strongly amenable at infinity is amenable whenever its full and reduced $C^*$-algebras coincide.

Operator Algebras · Mathematics 2022-02-01 Julian Kranz

We show that the group C*-algebra of any elementary amenable group is quasidiagonal. This is an offspring of recent progress in the classification theory of nuclear C*-algebras.

Operator Algebras · Mathematics 2014-09-24 Narutaka Ozawa , Mikael Rordam , Yasuhiko Sato