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Related papers: KMS states on finite-graph C*-algebras

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This paper presents, by example, an index theory appropriate to algebras without trace. Whilst we work exclusively with the Cuntz algebras the exposition is designed to indicate how to develop a general theory. Our main result is an index…

K-Theory and Homology · Mathematics 2008-02-29 A. L. Carey , J. Phillips , A. Rennie

We determine the factor generated by the GNS-representation defined by a KMS-weight for a generalized gauge action on a simple graph C*-algebra when the corresponding measure on the path space of the graph is conservative for the shift.…

Operator Algebras · Mathematics 2018-05-16 Klaus Thomsen

Given a graph $E$, an action of a group $G$ on $E$, and a $G$-valued cocycle $\phi$ on the edges of $E$, we define a C*-algebra denoted ${\cal O}_{G,E}$, which is shown to be isomorphic to the tight C*-algebra associated to a certain…

Operator Algebras · Mathematics 2016-09-16 Ruy Exel , Enrique Pardo

We prove that unital graph C*-algebras often admit a convenient decomposition into amalgamated free products. We use this to give a complete characterization of when a unital graph C*-algebra is residually finite-dimensional and when it is…

Operator Algebras · Mathematics 2026-03-05 Guillaume Bellier , Tatiana Shulman

We extend the usual theory of universal C*-algebras from generators and relations in order to allow some relations to be described using the strong operator topology. In particular, we can allow some infinite sum relations. We prove a…

Operator Algebras · Mathematics 2020-08-13 Giuliano Boava , Gilles G. de Castro

We compute the K-theory of the three C*-algebras associated to a rational function R acting on the Riemann sphere, its Fatou set, and its Julia set. The latter C*-algebra is a unital UCT Kirchberg algebra and is thus classified by its…

K-Theory and Homology · Mathematics 2023-07-26 Jeremy B. Hume

We pose a conjecture on the K-theory of the self-similar $k$-graph C*-algebra of a standard product of odometers. We generalize the C*-algebra $\mathcal{Q}_S$ to any subset of $\mathbb{N}^\times \setminus \{1\}$ and then realize it as the…

Operator Algebras · Mathematics 2020-03-24 Hui Li

We investigate conditions on a graph $C^*$-algebra for the existence of a faithful semifinite trace. Using such a trace and the natural gauge action of the circle on the graph algebra, we construct a smooth $(1,\infty)$-summable semfinite…

Functional Analysis · Mathematics 2007-05-23 David Pask , Adam Rennie

In order to realize all possible KMS-bundles on the Jiang-Su algebra, we introduce a class of C*-algebras which we call rationally approximately finite dimensional (RAF). Using these, we show that for a given proper simplex bundle $(S,…

Operator Algebras · Mathematics 2022-09-27 George A. Elliott , Yasuhiko Sato

Let $K$ be a compact metric space and let $\gamma = (\gamma_1, \dots, \gamma_n)$ be a system of proper contractions on $K$. We study a C*-algebra $\mathcal{MC}_{\gamma_1, \dots, \gamma_n}$ generated by all multiplication operators by…

Operator Algebras · Mathematics 2021-11-24 Hiroyasu Hamada

We introduce a property of C*-correspondences, which we call Condition (S), to serve as an analogue of Condition (L) of graphs. We use Condition (S) to prove a Cuntz-Krieger Uniqueness Theorem for Cuntz-Pimsner algebras and obtain…

Operator Algebras · Mathematics 2025-02-07 Menevşe Eryüzlü , Mark Tomforde

We generalise a number of classical results from the theory of KMS states to KMS weights in the setting of $C^{*}$-dynamical systems arising from a continuous groupoid homomorphism $c:\mathcal{G} \to \mathbb{R}$ on a locally compact second…

Operator Algebras · Mathematics 2021-04-15 Johannes Christensen

We study the KMS states and $KMS_{\infty}$ states of generalized gauge actions on the $C^*$-algebra of a pointed Cayley graph. Our results provide information for any finitely generated group, but they are only complete for nilpotent…

Operator Algebras · Mathematics 2017-05-02 Johannes Christensen , Klaus Thomsen

We develop notions of a representation of a topological graph E and of a covariant representation of a topological graph E which do not require the machinery of C*-correspondences and Cuntz-Pimsner algebras. We show that the C*-algebra…

Operator Algebras · Mathematics 2012-05-16 Hui Li , David Pask , Aidan Sims

In this monograph we undertake a comprehensive study of separable representations (as well as their unitary equivalence classes) of $C^*$-algebras associated to strongly connected finite $k$-graphs $\Lambda$. We begin with the…

Operator Algebras · Mathematics 2017-09-05 Carla Farsi , Elizabeth Gillaspy , Palle Jorgensen , Sooran Kang , Judith Packer

In a recent paper, Pardo and the first named author introduced a class of C*-algebras which which are constructed from an action of a group on a graph. This class was shown to include many C*-algebras of interest, including all Kirchberg…

Operator Algebras · Mathematics 2014-06-30 Ruy Exel , Charles Starling

Let $A$ be a unital C$^*$-algebra and let $\sigma$ be a one-parameter automorphism group of $A$. We consider $\operatorname{QSS}_\sigma(A)$, the set of all quantum symmetric states on $*_1^\infty A$ that are also KMS states (for a fixed…

Operator Algebras · Mathematics 2017-03-08 Ken Dykema , Kunal Mukherjee

Gauge-invariant polynomial functions of matrix and tensor variables capture combinatorial structures of gauge-string duality, which can be usefully organised using finite-dimensional associative algebras. I review recent work on eigenvalue…

High Energy Physics - Theory · Physics 2026-02-05 Sanjaye Ramgoolam

We investigate an extension of ideas of Atiyah-Patodi-Singer (APS) to a noncommutative geometry setting framed in terms of Kasparov modules. We use a mapping cone construction to relate odd index pairings to even index pairings with APS…

K-Theory and Homology · Mathematics 2008-02-04 A. L. Carey , J. Phillips , A. Rennie

The study of graph C*-algebras has a long history in operator algebras. Surprisingly, their quantum symmetries have never been computed so far. We close this gap by proving that the quantum automorphism group of a finite, directed graph…

Operator Algebras · Mathematics 2018-05-07 Simon Schmidt , Moritz Weber