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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 study the $C^*$-algebras of the \'etale groupoids defined by the asymptotic equivalence relations for hyperbolic automorphisms on the two-dimensional torus. The algebras are proved to be four-dimensional non-commutative tori by an…

Operator Algebras · Mathematics 2020-12-07 Kengo Matsumoto

This paper is a continuation of the paper entitled "Subshifts, $\lambda$-graph bisystems and $C^*$-algebras", arXiv:1904.06464. A $\lambda$-graph bisystem consists of a pair of two labeled Bratteli diagrams satisfying certain compatibility…

Operator Algebras · Mathematics 2019-06-06 Kengo Matsumoto

Under mild assumptions, we characterise modules with projective resolutions of length n in the target category of filtrated K-theory over a finite topological space in terms of two conditions involving certain Tor-groups. We show that the…

Operator Algebras · Mathematics 2014-02-11 Rasmus Bentmann

In this paper, we apply the theory of inverse semigroups to the $C^{*}$-algebra $U[\mathbb{Z}]$ considered in \cite{Cuntz}. We show that the $C^{*}$-algebra $U[\mathbb{Z}]$ is generated by an inverse semigroup of partial isometries. We…

Operator Algebras · Mathematics 2011-04-13 S. Sundar

We compute the K-groups of C^*-algebras arising from one-dimensional generalized solenoids. The results show that Ruelle algebras from one-dimensional generalized solenoids are one-dimensional generalizations of Cuntz-Krieger algebras.

Operator Algebras · Mathematics 2007-05-23 Inhyeop Yi

Following Robert's [26], we study the structure of unitary groups and groups of approximately inner automorphisms of unital $C^*$-algebras, taking advantage of the former being Banach-Lie groups. For a given unital $C^*$-algebra $A$, we…

Operator Algebras · Mathematics 2025-01-06 Hiroshi Ando , Michal Doucha

We introduce a general class of automorphisms of rotation algebras, the noncommutative Furstenberg transformations. We prove that fully irrational noncommutative Furstenberg transformations have the tracial Rokhlin property, which is a…

Operator Algebras · Mathematics 2007-05-23 Hiroyuki Osaka , N. Christopher Phillips

We establish a formula for the L-theory spectrum of real $C^*$-algebras from which we deduce a presentation of the L-groups in terms of the topological K-groups, extending all previously known results of this kind. Along the way, we extend…

K-Theory and Homology · Mathematics 2022-08-24 Markus Land , Thomas Nikolaus , Marco Schlichting

Under suitable conditions, a substitution tiling gives rise to a Smale space, from which three equivalence relations can be constructed, namely the stable, unstable, and asymptotic equivalence relations. We denote with $S$, $U$, and $A$…

Operator Algebras · Mathematics 2018-09-25 Daniel Gonçalves , Maria Ramirez-Solano

To a large class of graphs of groups we associate a C*-algebra universal for generators and relations. We show that this C*-algebra is stably isomorphic to the crossed product induced from the action of the fundamental group of the graph of…

Operator Algebras · Mathematics 2021-07-27 Nathan Brownlowe , Alexander Mundey , David Pask , Jack Spielberg , Anne Thomas

Suppose that A is a C*-algebra for which A is isomorphic to A tensor Z, where Z is the Jiang-Su algebra: a unital, simple, stably finite, separable, nuclear, infinite dimensional C*-algebra with the same Elliott invariant as the complex…

Operator Algebras · Mathematics 2010-11-24 Mikael Rordam

We describe a class of rank-2 graphs whose C^*-algebras are AT algebras. For a subclass which we call rank-2 Bratteli diagrams, we compute the K-theory of the C*-algebra. We identify rank-2 Bratteli diagrams whose C*-algebras are simple and…

Operator Algebras · Mathematics 2007-05-23 David Pask , Iain Raeburn , Mikael Rordam , Aidan Sims

In this paper, we study the boundary quotient C*-algebras associated to products of odometers. One of our main results shows that the boundary quotient C*-algebra of the standard product of $k$ odometers over $n_i$-letter alphabets ($1\le…

Operator Algebras · Mathematics 2017-05-08 Hui Li , Dilian Yang

We present and study C*-algebras generated by "periodic weighted creation operators" on the Fock space associated with an automorphism $\alpha$ on a C*-algebra $A$. These algebras can be viewed as generalized Bunce-Deddens algebras…

Operator Algebras · Mathematics 2007-05-23 Baruch Solel

We prove that twisted groupoid C*-algebras are characterised, up to isomorphism, by having Cartan semigroups, a natural generalisation of normaliser semigroups of Cartan subalgebras. This extends the classic Kumjian-Renault theory to…

Operator Algebras · Mathematics 2025-04-25 Tristan Bice , Lisa Orloff Clark , Ying-Fen Lin , Kathryn McCormick

We introduce a notion of approximate ideal structure for a $C^*$-algebra, and use it as a tool to study $K$-theory groups. The notion is motivated by the classical Mayer-Vietoris sequence, by the theory of nuclear dimension as introduced by…

Operator Algebras · Mathematics 2020-05-12 Rufus Willett

We prove that Kellendonk's $C^*$-algebra of an aperiodic and repetitive tiling with finite local complexity is classifiable by the Elliott invariant. Our result follows from showing that tiling $C^*$-algebras are $\mathcal{Z}$-stable, and…

Operator Algebras · Mathematics 2019-09-11 Luke J. Ito , Michael F. Whittaker , Joachim Zacharias

We introduce a class of generalized universal irrational rotation $C^*$-algebras $A_{\theta,\gamma}=C^*(x,w)$ which is characterized by the relations $w^*w=ww^*=1$, $x^*x=\gamma(w)$, $xx^*=\gamma(e^{-2\pi i\theta}w)$, and $xw=e^{-2\pi…

Operator Algebras · Mathematics 2012-10-18 Junsheng Fang , Chunlan Jiang , Huaxin Lin , Feng Xu

It is now well known that a simple graph $C^*$-algebra $C^*(E)$ of a directed graph $E$ is either AF or purely infinite. In this paper, we address the question of whether this is the case for labeled graph $C^*$-algebras recently introduced…

Operator Algebras · Mathematics 2016-03-01 Ja A Jeong , Eun Ji Kang , Sun Ho Kim , Gi Hyun Park