English
Related papers

Related papers: Coverings of k-graphs

200 papers

We address the classification problem for graph $C^*$-algebras of finite graphs (finitely many edges and vertices), containing the class of Cuntz-Krieger algebras as a prominent special case. Contrasting earlier work, we do not assume that…

Operator Algebras · Mathematics 2018-03-05 Søren Eilers , Gunnar Restorff , Efren Ruiz , Adam P. W. Sørensen

Following our previous works on $C^*$-graph algebras and the associated Cuntz-Krieger graph families, in this paper we will try to have a look at the colored version of these structures and to see what a $C^*$-colored graph algebra might…

Operator Algebras · Mathematics 2025-04-25 Farrokh Razavinia

Every directed graph defines a Hilbert space and a family of weighted shifts that act on the space. We identify a natural notion of periodicity for such shifts and study their C*-algebras. We prove the algebras generated by all shifts of a…

Operator Algebras · Mathematics 2007-05-23 David W. Kribs , Baruch Solel

Associating graph algebras to directed graphs leads to both covariant and contravariant functors from suitable categories of graphs to the category k-Alg of algebras and algebra homomorphisms. As both functors are often used at the same…

Rings and Algebras · Mathematics 2026-04-30 Gilles G. de Castro , Francesco D'Andrea , Piotr M. Hajac

We develop new techniques for the construction and classification of representations of row-finite and locally convex higher-rank graph C*-algebras O. This class includes Cuntz--Krieger algebras associated to row-finite directed graphs. Our…

Operator Algebras · Mathematics 2026-04-20 Arnaud Brothier , Aidan Sims , Dilshan Wijesena

We develop a notion of a generalized Cuntz-Krieger family of projections and partial isometries where the range of the partial isometries need not have trivial intersection. We associate to these generalized Cuntz-Krieger families a…

Operator Algebras · Mathematics 2010-01-05 Benton L. Duncan

The graph C*-algebra of a directed graph E is the universal C*-algebra generated by a family of partial isometries satisfying relations which reflect the path structure of E. In the first part of this paper we consider coverings of directed…

Operator Algebras · Mathematics 2007-05-23 Klaus Deicke , David Pask , Iain Raeburn

We investigate which topological spaces can be constructed as topological realisations of higher-rank graphs. We describe equivalence relations on higher-rank graphs for which the quotient is again a higher-rank graph, and show that…

Operator Algebras · Mathematics 2016-06-09 Alex Kumjian , David Pask , Aidan Sims , Michael F. Whittaker

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

We define the categorical cohomology of a k-graph \Lambda\ and show that the first three terms in this cohomology are isomorphic to the corresponding terms in the cohomology defined in our previous paper. This leads to an alternative…

Operator Algebras · Mathematics 2013-08-15 Alex Kumjian , David Pask , Aidan Sims

We consider two Z/2Z-actions on the Podles generic quantum spheres. They yield, as noncommutative quotient spaces, the Klimek-Lesniewski q-disc and the quantum real projective space, respectively. The C*-algebras of all these quantum spaces…

Quantum Algebra · Mathematics 2009-11-07 P. M. Hajac , R. Matthes , W. Szymanski

A functor from the category of directed trees with inclusions to the category of commutative C*-algebras with injective *-homomorphisms is constructed. This is used to define a functor from the category of directed graphs with inclusions to…

Operator Algebras · Mathematics 2007-05-23 Jack Spielberg

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

Building on recent work of Robertson and Steger, we associate a C*-algebra to a combinatorial object which may be thought of as a higher rank graph. This C*-algebra is shown to be isomorphic to that of the associated path groupoid.…

Operator Algebras · Mathematics 2007-05-23 Alex Kumjian , David Pask

Cuntz algebras $\mathcal{O}_n$, $n>1$, are celebrated examples of a separable infinite simple C*-algebra with a number of fascinating properties. Their K-theory allows an embedding of $\mathcal O_m$ in $\mathcal O_n$ whenever $n-1$ divides…

Operator Algebras · Mathematics 2025-02-21 Piotr M. Hajac , Yang Liu

We appeal to results from combinatorial random matrix theory to deduce that various random graph $\mathrm{C}^*$-algebras are asymptotically almost surely Kirchberg algebras with trivial $K_1$. This in particular implies that, with high…

Operator Algebras · Mathematics 2025-05-22 Bhishan Jacelon , Igor Khavkine

Given an arbitrary countable directed graph $G$ we prove the C*-envelope of the tensor algebra $T_+(G)$ coincides with the universal Cuntz-Krieger algebra associated with $G$. Our approach is concrete in nature and does not rely on Hilbert…

Operator Algebras · Mathematics 2007-05-23 Elias Katsoulis , David Kribs

We provide inverse semigroup and groupoid models for the Toeplitz and Cuntz-Krieger algebras of finitely aligned higher-rank graphs. Using these models, we prove a uniqueness theorem for the Cuntz-Krieger algebra.

Operator Algebras · Mathematics 2007-05-23 Cynthia Farthing , Paul S. Muhly , Trent Yeend

An action of Z^l by automorphisms of a k-graph induces an action of Z^l by automorphisms of the corresponding k-graph C*-algebra. We show how to construct a (k+l)-graph whose C*-algebra coincides with the crossed product of the original…

Operator Algebras · Mathematics 2007-06-26 Cynthia Farthing , David Pask , Aidan Sims

We define branching systems for finitely aligned higher-rank graphs. From these we construct concrete representations of higher-rank graph C*-algebras on Hilbert spaces. We prove a generalized Cuntz-Krieger uniqueness theorem for periodic…

Operator Algebras · Mathematics 2017-03-17 Daniel Gonçalves , Hui Li , Danilo Royer