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Related papers: Computing K-theory and Ext for graph C*-algebras

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We generalize the classification result of Restorff on Cuntz-Krieger algebras to cover all unital graph C*-algebras with real rank zero, showing that Morita equivalence in this case is determined by ordered, filtered K-theory as conjectured…

Operator Algebras · Mathematics 2015-07-09 Søren Eilers , Gunnar Restorff , Efren Ruiz , Adam P. W. Sørensen

In an earlier paper, the authors introduced partial translation algebras as a generalisation of group C*-algebras. Here we establish an extension of partial translation algebras, which may be viewed as an excision theorem in this context.…

Operator Algebras · Mathematics 2013-04-29 Jacek Brodzki , Graham A. Niblo , Nick Wright

We provide a Cuntz-Pimsner model for graph of groups $C^*$-algebras. This allows us to compute the $K$-theory of a range of examples and show that graph of groups $C^*$-algebras can be realised as Exel-Pardo algebras. We also make a…

Operator Algebras · Mathematics 2021-07-27 Alexander Mundey , Adam Rennie

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

These are notes on twisted K-homology theory and twisted Ext-theory from the C*-algebra viewpoint, part of a series of talks on ``C*-algebras, noncommutative geometry and K-theory'', primarily for physicists.

High Energy Physics - Theory · Physics 2007-05-23 V. Mathai , I. M. Singer

In this paper we give a formula for the $K$-theory of the $C^*$-algebra of a weakly left-resolving labelled space. This is done by realising the $C^*$-algebra of a weakly left-resolving labelled space as the Cuntz-Pimsner algebra of a…

Operator Algebras · Mathematics 2017-05-10 Teresa Bates , Toke Meier Carlsen , David Pask

Given a $k$-graph $\Lambda$ and an element $p$ of $\NN^k$, we define the dual $k$-graph, $p\Lambda$. We show that when $\Lambda$ is row-finite and has no sources, the $C^*$-algebras $C^*(\Lambda)$ and $C^*(p\Lambda)$ coincide. We use this…

Operator Algebras · Mathematics 2007-05-23 Stephen Allen , David Pask , Aidan Sims

We show that the long exact sequence for K-groups of Leavitt path algebras deduced by Ara, Brustenga, and Cortinas extends to Leavitt path algebras of countable graphs with infinite emitters in the obvious way. Using this long exact…

K-Theory and Homology · Mathematics 2015-03-27 James Gabe , Efren Ruiz , Mark Tomforde , Tristan Whalen

We compute the K-theory of C*-algebras generated by the left regular representation of left Ore semigroups satisfying certain regularity conditions. Our result describes the K-theory of these semigroup C*-algebras in terms of the K-theory…

Operator Algebras · Mathematics 2013-05-28 Joachim Cuntz , Siegfried Echterhoff , Xin Li

For a finitely aligned k-graph $\Lambda$ with X a set of vertices in $\Lambda$ we define a universal C*-algebra called $C^*(\Lambda,X)$ generated by partial isometries. We show that $C^*(\Lambda,X)$ is isomorphic to the corner…

Operator Algebras · Mathematics 2007-05-23 Stephen Allen

We compute K-theory for ring C*-algebras in the case of higher roots of unity and thereby completely determine the K-theory for ring C*-algebras attached to rings of integers in arbitrary number fields.

Operator Algebras · Mathematics 2025-04-08 Xin Li , Wolfgang Lück

We introduce certain $C^*$-algebras and $k$-graphs associated to $k$ finite dimensional unitary representations $\rho_1,...,\rho_k$ of a compact group $G$. We define a higher rank Doplicher-Roberts algebra $\mathcal{O}_{\rho_1,...,\rho_k}$,…

Operator Algebras · Mathematics 2020-06-26 Valentin Deaconu

To an arbitrary directed graph we associate a row-finite directed graph whose C*-algebra contains the C*-algebra of the original graph as a full corner. This allows us to generalize results for C*-algebras of row-finite graphs to…

Operator Algebras · Mathematics 2007-05-23 D. Drinen , M. Tomforde

We present an axiomatic frame (in Prt I of this book) in which many results of the K-theory for C*-algebras are proved. Then we construct an example for this axiomatic theory (in Part II), which generalizes the classical theory for…

Operator Algebras · Mathematics 2013-11-19 Corneliu Constantinescu

We introduce filtered algebraic $K$-theory of a ring $R$ relative to a sublattice of ideals. This is done in such a way that filtered algebraic $K$-theory of a Leavitt path algebra relative to the graded ideals is parallel to the gauge…

Rings and Algebras · Mathematics 2021-09-20 Søren Eilers , Gunnar Restorff , Efren Ruiz , Adam P. W. Sørensen

We give a complete $K$-theoretical description of when an extension of two simple graph $C^{*}$-algebras is again a graph $C^{*}$-algebra.

Operator Algebras · Mathematics 2020-07-07 Søren Eilers , James Gabe , Takeshi Katsura , Efren Ruiz , Mark Tomforde

Given a row-finite, source-free, graph of rank k, we extend the definition of reduction introduced by Eckhardt et al. This constitutes a large step forward in the extension of the geometric classification of finite directed graph…

Operator Algebras · Mathematics 2024-06-18 S. Joseph Lippert

We continue the study of the effective content of $K$-theory for C*-algebras, with a focus on AF algebras. We show that from a c.e. presentation of an AF algebra it is possible to compute a representation of the algebra as an inductive…

Operator Algebras · Mathematics 2026-02-09 Christopher J. Eagle , Isaac Goldbring , Timothy H. McNicholl

We show that the C*-algebra of a row-finite source-free k-graph is Rieffel-Morita equivalent to a crossed product of an AF algebra by the fundamental group of the k-graph. When the k-graph embeds in its fundamental groupoid, this AF algebra…

Operator Algebras · Mathematics 2024-03-05 Nathan Brownlowe , Alex Kumjian , David Pask , Aidan Sims

Using a result of Vdovina, we may associate to each complete connected bipartite graph $\kappa$ a $2$-dimensional square complex, which we call a tile complex, whose link at each vertex is $\kappa$. We regard the tile complex in two…

Combinatorics · Mathematics 2021-02-18 S. A. Mutter