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We consider self-similar actions of groupoids on the path spaces of finite directed graphs, and construct examples of such self-similar actions using a suitable notion of graph automaton. Self-similar groupoid actions have a Cuntz-Pimsner…

Operator Algebras · Mathematics 2019-03-05 Marcelo Laca , Iain Raeburn , Jacqui Ramagge , Michael F. Whittaker

For every Hilbert bimodule over a C*-algebra, there are natural gauge actions of the circle on the associated Toeplitz algebra and Cuntz-Pimsner algebra, and hence natural dynamics obtained by lifting these gauge actions to actions of the…

Operator Algebras · Mathematics 2014-03-12 Zahra Afsar , Astrid an Huef , Iain Raeburn

We consider a family of Cuntz-Pimsner algebras associated to self-similar group actions, and their Toeplitz analogues. Both families carry natural dynamics implemented by automorphic actions of the real line, and we investigate the…

Operator Algebras · Mathematics 2014-05-20 Marcelo Laca , Iain Raeburn , Jacqui Ramagge , Michael F. Whittaker

We consider a finite directed graph E, and the gauge action on its Toeplitz-Cuntz-Krieger algebra, viewed as an action of R. For inverse temperatures larger than a critical value \beta_c, we give an explicit construction of all the…

Operator Algebras · Mathematics 2012-05-11 Astrid an Huef , Marcelo Laca , Iain Raeburn , Aidan Sims

We study the equilibrium or KMS states of the Toeplitz C*-algebra of a finite higher-rank graph which is reducible. The Toeplitz algebra carries a gauge action of a higher-dimensional torus, and a dynamics arises by choosing an embedding of…

Operator Algebras · Mathematics 2016-10-24 Astrid an Huef , Sooran Kang , Iain Raeburn

Several authors have recently been studying the equilibrium or KMS states on the Toeplitz algebras of finite higher-rank graphs. For graphs of rank one (that is, for ordinary directed graphs), there is a natural dynamics obtained by lifting…

Operator Algebras · Mathematics 2014-10-02 Astrid an Huef , Sooran Kang , Iain Raeburn

We introduce the notion of a self-similar action of a groupoid $G$ on a finite higher-rank graph. To these actions we associate a compactly aligned product system of Hilbert bimodules, and thereby obtain corresponding universal…

Operator Algebras · Mathematics 2024-07-12 Zahra Afsar , Nathan Brownlowe , Jacqui Ramagge , Michael F. Whittaker

We consider a family of operator-algebraic dynamical systems involving the Toeplitz algebras of higher-rank graphs. We explicitly compute the KMS states (equilibrium states) of these systems built from small graphs with up to four connected…

Operator Algebras · Mathematics 2019-05-06 Astrid an Huef , Iain Raeburn

We consider the dynamics on the C*-algebras of finite graphs obtained by lifting the gauge action to an action of the real line. Enomoto, Fujii and Watatani proved that if the vertex matrix of the graph is irreducible, then the dynamics on…

Operator Algebras · Mathematics 2014-05-12 Astrid an Huef , Marcelo Laca , Iain Raeburn , Aidan Sims

Consider a higher-rank graph of rank k. Both the Cuntz-Krieger algebra and the Toeplitz-Cuntz-Krieger algebra of the graph carry natural gauge actions of the torus T^k, and restricting these gauge actions to one-parameter subgroups of T^k…

Operator Algebras · Mathematics 2013-01-01 Astrid an Huef , Marcelo Laca , Iain Raeburn , Aidan Sims

We consider a family of $*$-commuting local homeomorphisms on a compact space, and build a compactly aligned product system of Hilbert bimodules (in the sense of Fowler). This product system has a Nica-Toeplitz algebra and a Cuntz-Pimsner…

Operator Algebras · Mathematics 2018-04-18 Zahra Afsar , Astrid an Huef , Iain Raeburn

We study KMS states on finite-graph C*-algebras with sinks and sources. We compare finite-graph C*-algebras with C*-algebras associated with complex dynamical systems of rational functions. We show that if the inverse temperature $\beta$ is…

Operator Algebras · Mathematics 2010-07-27 Tsuyoshi Kajiwara , Yasuo Watatani

We examine Nica-Pimsner algebras associated with semigroup actions of $\mathbb{Z}_+^n$ on a C*-algebra $A$ by $*$-endomorphisms. We give necessary and sufficient conditions on the dynamics for exactness and nuclearity of the Nica-Pimsner…

Operator Algebras · Mathematics 2018-08-17 Evgenios T. A. Kakariadis

The structure of KMS states of Toeplitz algebras associated to finite graphs equipped with the gauge action is determined by an Huef--Laca--Raeburn--Sims. Their results imply that extremal KMS states of type I correspond to vertices, while…

Operator Algebras · Mathematics 2022-01-05 Takuya Takeishi

We study the KMS states on local quantum Cuntz-Krieger algebras associated to quantum graphs. Using their isomorphism to the Cuntz-Pimsner algebra of the quantum edge correspondence, we show that the general criteria for KMS states can be…

Operator Algebras · Mathematics 2025-07-17 Manish Kumar , Mateusz Wasilewski

The Toeplitz algebra $\mathcal{T}C^{*}(\Lambda)$ for a finite $k$-graph $\Lambda$ is equipped with a continuous one-parameter group $\alpha^{r}$ for each $ r\in \mathbb{R}^{k}$, obtained by composing the map $\mathbb{R} \ni t \to…

Operator Algebras · Mathematics 2020-01-16 Johannes Christensen

In recent joint work of the authors with Laca, we precisely formulated the notion of partition function in the context of C*-dynamical systems. Here, we compute the partition functions of C*-dynamical systems arising from Toeplitz algebras…

Operator Algebras · Mathematics 2021-03-05 Chris Bruce , Takuya Takeishi

Given a positive function on the set of edges of an arbitrary directed graph $E=(E^0,E^1)$, we define a one-parameter group of automorphisms on the C*-algebra of the graph $C^*(E)$, and study the problem of finding KMS states for this…

Operator Algebras · Mathematics 2019-09-11 Gilles de Castro , Fernando Mortari

We examine the theory of the KMS states on Pimsner algebras arising from multivariable unital C*-dynamical systems. As an application we show that Pimsner algebras of piecewise conjugate classical systems attain the same KMS states, even…

Operator Algebras · Mathematics 2018-08-17 Evgenios T. A. Kakariadis

We study invariance of KMS states on graph C*-algebras coming from strongly connected and circulant graphs under the classical and quantum symmetry of the graphs. We show that the unique KMS state for strongly connected graphs is invariant…

Operator Algebras · Mathematics 2025-12-09 Soumalya Joardar , Arnab Mandal
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