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Related papers: The Property of Rapid Decay for Discrete Quantum G…

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We generalize the notion of rapid decay property for a group $G$ to pairs of groups $(G,H)$ where $H$ is a finitely generated subgroup of $G$, where typically the subgroup $H$ does not have rapid decay. We deduce some isomorphisms in…

Operator Algebras · Mathematics 2026-04-22 Indira Chatterji , Benjamin Zarka

We present a modified version of the definition of property RD for discrete quantum groups given by Vergnioux in order to accommodate examples of non-unimodular quantum groups. Moreover we extend the construction of spectral triples…

Operator Algebras · Mathematics 2014-06-04 Jyotishman Bhowmick , Christian Voigt , Joachim Zacharias

Let Gamma be a discrete group satisfying the rapid decay property with respect to a length function which is conditionally negative. Then the reduced C*-algebra of Gamma has the metric approximation property. The central point of our proof…

Group Theory · Mathematics 2016-09-07 Jacek Brodzki , Graham Niblo

We give a simple definition of property T for discrete quantum groups. We prove the basic expected properties: discrete quantum groups with property T are finitely generated and unimodular. Moreover we show that, for "I.C.C." discrete…

Operator Algebras · Mathematics 2008-12-04 Pierre Fima

We introduce the analog of Bohr compactification for discrete quantum groups on C*-algebra level. The cases of unimodular and general C*-algebraic discrete quantum groups are treated separately. The passage from the former case to the…

Operator Algebras · Mathematics 2016-08-15 P. M. Sołtan

We investigate connections between various rigidity and softness properties for discrete quantum groups. After introducing a notion of residual finiteness, we show that it implies the Kirchberg factorization property for the discrete…

Quantum Algebra · Mathematics 2020-07-07 Angshuman Bhattacharya , Michael Brannan , Alexandru Chirvasitu , Shuzhou Wang

We explain some simple methods to establish the property of Rapid Decay for a number of groups arising geometrically. We also give new examples of groups with the property of Rapid Decay. In particular we establish the property of Rapid…

Group Theory · Mathematics 2007-05-23 Indira Chatterji , Kim Ruane

We show that the reduced groupoid C*-algebras of continuous fields of \'etale groupoids satisfying the rapid decay property yield continuous fields of C*-algebras. This establishes a new sufficient criterion that applies in the non-amenable…

Operator Algebras · Mathematics 2025-09-30 Tom Stoiber

In this short article, we obtained some equivalent formulations of property $T$ for a general locally compact quantum group $\mathbb{G}$, in terms of the full quantum group $C^*$-algebras $C_0^\mathrm{u}(\widehat{\mathbb{G}})$ and the…

Quantum Algebra · Mathematics 2015-10-07 Xiao Chen , Chi-Keung Ng

We classify all compact quantum groups whose C*-algebra sits inside that of the free unitary quantum groups $U_{N}^{+}$. In other words, we classify all discrete quantum subgroups of $\widehat{U}_{N}^{+}$, thereby proving a quantum variant…

Operator Algebras · Mathematics 2024-03-05 Amaury Freslon , Moritz Weber

In this paper we study the part of the $K$-theory of the reduced $C^*$-algebra arising from torsion elements of the group, and in particular we study the pairing of $K$-theory with traces and when traces can detect certain $K$-theory…

K-Theory and Homology · Mathematics 2016-09-30 Sherry Gong

We prove several results on the permanence of weak amenability and the Haagerup property for discrete quantum groups. In particular, we improve known facts on free products by allowing amalgamation over a finite quantum subgroup. We also…

Operator Algebras · Mathematics 2014-11-18 Amaury Freslon

This is an introduction to the Rapid Decay property, with a survey of known results and equivalent definitions of this property. We also discuss in details the easy case when G = Z. Everything in this paper is well-known by different sets…

Group Theory · Mathematics 2016-05-10 Indira Chatterji

We study the Haagerup--Kraus approximation property for locally compact quantum groups, generalising and unifying previous work by Kraus--Ruan and Crann. Along the way we discuss how multipliers of quantum groups interact with the…

Operator Algebras · Mathematics 2024-01-05 Matthew Daws , Jacek Krajczok , Christian Voigt

We study Property (T) for locally compact quantum groups, providing several new characterisations, especially related to operator algebraic ergodic theory. Quantum Property (T) is described in terms of the existence of various Kazhdan type…

Operator Algebras · Mathematics 2017-04-26 Matthew Daws , Adam Skalski , Ami Viselter

The following paper is devoted to the study of type I locally compact quantum groups. We show how various operators related to the modular theory of the Haar integrals on $\mathbb{G}$ and $\widehat{\mathbb{G}}$ act on the level of direct…

Quantum Algebra · Mathematics 2020-08-06 Jacek Krajczok

We obtain two related characterizations of discrete quantum groups and discrete quantum groups of Kac type as allegorical group objects in the symmetric monoidal dagger category of quantum sets and relations, of interest to quantum…

Quantum Algebra · Mathematics 2025-12-12 Alexandru Chirvasitu , Andre Kornell

We describe representations of groupoid C*-algebras on Hilbert modules over arbitrary C*-algebras by a universal property. For Hilbert space representations, our universal property is equivalent to Renault's Integration-Disintegration…

Operator Algebras · Mathematics 2019-04-30 Alcides Buss , Rohit Holkar , Ralf Meyer

We prove a Delorme-Guichardet type theorem for discrete quantum groups expressing property (T) of the quantum group in question in terms of its first cohomology groups. As an application, we show that the first L^2-Betti number of a…

Operator Algebras · Mathematics 2011-05-18 David Kyed

We give a decomposition of the equivariant Kasparov category for discrete quantum group with torsions. As an outcome, we show that the crossed product by a discrete quantum group in a certain class preserves the UCT. We then show that…

Operator Algebras · Mathematics 2021-03-22 Yuki Arano , Adam Skalski
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