Simplicity of C*‐algebras associated to higher‐rank graphs
- D. Robertson, A. Sims
- Mathematics
- 7 February 2006
We prove that if Λ is a row‐finite k‐graph with no sources, then the associated C*‐algebra is simple if and only if Λ is cofinal and satisfies Kumjian and Pask's aperiodicity condition, known as…
Zappa-Sz\'ep products of semigroups and their C*-algebras
- Nathan Brownlowe, Jacqui Ramagge, D. Robertson, Michael F. Whittaker
- Mathematics
- 2 September 2013
The extension class and KMS states for Cuntz--Pimsner algebras of some bi-Hilbertian bimodules
- A. Rennie, D. Robertson, A. Sims
- Mathematics
- 22 January 2015
For bi-Hilbertian $A$-bimodules, in the sense of Kajiwara--Pinzari--Watatani, we construct a Kasparov module representing the extension class defining the Cuntz--Pimsner algebra. The construction…
Groupoid algebras as Cuntz-Pimsner algebras
- A. Rennie, D. Robertson, A. Sims
- Mathematics
- 28 February 2014
We show that if $G$ is a second countable locally compact Hausdorff \'etale groupoid carrying a suitable cocycle $c:G\to\mathbb{Z}$, then the reduced $C^*$-algebra of $G$ can be realised naturally as…
Simplicity of C*-algebras associated to row-finite locally convex higher-rank graphs
- D. Robertson, A. Sims
- Mathematics
- 1 August 2007
In a previous work, the authors showed that the C*-algebra C*(Λ) of a row-finite higher-rank graph Λ with no sources is simple if and only if Λ is both cofinal and aperiodic. In this paper, we…
A new look at crossed product correspondences and associated C*-algebras
- Erik B'edos, S. Kaliszewski, John Quigg, D. Robertson
- Mathematics
- 4 September 2014
Groupoid Fell bundles for product systems over quasi-lattice ordered groups
- A. Rennie, D. Robertson, A. Sims
- MathematicsMathematical Proceedings of the Cambridge…
- 22 January 2015
Abstract Consider a product system over the positive cone of a quasi-lattice ordered group. We construct a Fell bundle over an associated groupoid so that the cross-sectional algebra of the bundle is…
Coactions on Cuntz-Pimsner Algebras
- S. Kaliszewski, John Quigg, D. Robertson
- Mathematics
- 26 April 2012
We investigate how a correspondence coaction gives rise to a coaction on the associated Cuntz-Pimsner algebra. We apply this to recover a recent result of Hao and Ng concerning Cuntz-Pimsner algebras…
Zappa–Szép product groupoids and $$C^*$$C∗-blends
- Nathan Brownlowe, D. Pask, Jacqui Ramagge, D. Robertson, Michael F. Whittaker
- Mathematics
- 14 July 2015
We study the external and internal Zappa–Szép product of topological groupoids. We show that under natural continuity assumptions the Zappa–Szép product groupoid is étale if and only if the…
Reconstructing directed graphs from generalized gauge actions on their Toeplitz algebras
- Nathan Brownlowe, Marcelo Laca, D. Robertson, A. Sims
- MathematicsProceedings of the Royal Society of Edinburgh…
- 21 December 2018
Abstract We show how to reconstruct a finite directed graph E from its Toeplitz algebra, its gauge action, and the canonical finite-dimensional abelian subalgebra generated by the vertex projections.…
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