Mathematics
Te Tari Pāngarau me te Tatauranga
Department of Mathematics & Statistics

Archived research seminars in Mathematics

Seminars 1 to 50

Next 50 seminars
Semibranching function systems and the representations of Cuntz-Krieger algebra associated to higher-rank graphs III

Sooran Kang

University of Otago

Date: Tuesday 13 October 2015

151012102710
Semibranching function systems and the representations of Cuntz-Krieger algebra associated to higher-rank graphs II

Sooran Kang

University of Otago

Date: Tuesday 6 October 2015

151012102605
Semibranching function systems and the representations of Cuntz-Krieger algebra associated to higher-rank graphs.

Sooran Kang

University of Otago

Date: Tuesday 29 September 2015

150928150631
REALISING THE TOEPLITZ ALGEBRA OF A HIGHER-RANK GRAPH AS A CUNTZ-KRIEGER ALGEBRA II

Yosafat Pangalela (Oscar)

University of Otago

Date: Tuesday 22 September 2015

150903145947
REALISING THE TOEPLITZ ALGEBRA OF A HIGHER-RANK GRAPH AS A CUNTZ-KRIEGER ALGEBRA I

Yosafat Pangalela (Oscar)

University of Otago

Date: Tuesday 15 September 2015

150903145823
Equilibrium states on C*-algebras associated to reducible 1-graphs.

Iain Raeburn

University of Otago

Date: Tuesday 8 September 2015

150903145226
Purely infinite groupoid C*-algebras

Jonathan Brown

University of Dayton, Ohio

Date: Tuesday 26 May 2015

Many C*-algebras, including graph and higher-rank graph algebras, have etale groupoid models. So the classification of etale groupoid C*-algebras has wide applicability. The seminal work of Kirchberg and Phillips showed that simple nuclear purely infinite C*-algebras (Kirchberg Algebras) satisfying the UCT can be classified by their ordered K-theory. It is thus interesting from a classification perspective to know which etale groupoids yield Kirchberg algebras and for this it is essential to understand precisely when an etale groupoid yields a purely infinite C*-algebra. In this talk we show that a simple etale groupoid C*-algebra is purely infinite if the nonzero positive elements of a canonical Cartan MASA are infinite. We further reduce these criteria in the case of higher rank graph groupoids. We also provide a general construction that shows we can use etale groupoids to provide concrete models for many Kirchberg algebras. We apply this construction to the groupoids associated to Bratteli diagrams and deduce that for every simple dimension group D not equal to Z, the stable Kirchberg algebra with K-theory (D, {0}) can be realised as the C * -algebra of an amenable principal groupoid.
150526100101
KMS states associated to finite directed graphs with a non-gauge action II

Richard McNamara

University of Otago

Date: Tuesday 5 May 2015

150428164327
KMS states associated to finite directed graphs with a non-gauge action I

Richard McNamara

University of Otago

Date: Tuesday 28 April 2015

150428164202
C*-algebras generated by semigroups of partial isometries

Ilija Tolich

University of Otago

Date: Tuesday 21 April 2015

150421100645
C*-algebras generated by semigroups of partial isometries

Ilija Tolich

University of Otago

Date: Tuesday 14 April 2015

150413125016
Equilibrium states on C*-algebras associated to local homeomorphisms II

Zahra Afsar

University of Otago

Date: Tuesday 31 March 2015

For a local homeomorphism, there is an associated Hilbert bimodule over a $C^*$-algebra. This Hilbert bimodule gives two main $C^*$-algebras: the Toeplitz algebra and its quotient the Cuntz-Pimsner algebra. Both algebras carry natural gauge actions of the circle, and hence one can obtain natural dynamics by lifting these actions to actions of the real line. In the literature, equilibrium states of Cuntz-Pimsner algebra are widely investigated. Recent works show that the Toeplitz algebra is expected to have many more equilibrium states. We focus on studying equilibrium states of the Toeplitz algebra. Then we reconcile our results in the Toeplitz algebra with those recent results of the Cuntz-Pimsner algebra. In this talk, after a brief explanation of basic definitions and notation, I will describe some of our main results.
150323145504
Equilibrium states on C*-algebras associated to local homeomorphisms

Zahra Afsar

University of Otago

Date: Wednesday 11 March 2015

For a local homeomorphism, there is an associated Hilbert bimodule over a $C^*$-algebra. This Hilbert bimodule gives two main $C^*$-algebras: the Toeplitz algebra and its quotient the Cuntz-Pimsner algebra. Both algebras carry natural gauge actions of the circle, and hence one can obtain natural dynamics by lifting these actions to actions of the real line. In the literature, equilibrium states of Cuntz-Pimsner algebra are widely investigated. Recent works show that the Toeplitz algebra is expected to have many more equilibrium states. We focus on studying equilibrium states of the Toeplitz algebra. Then we reconcile our results in the Toeplitz algebra with those recent results of the Cuntz-Pimsner algebra. In this talk, after a brief explanation of basic definitions and notation, I will describe some of our main results.
150304140847
Construction of a k-graph from a k-colored graph

Iain Raeburn

University of Otago

Date: Thursday 13 November 2014

141116140252
Visualization of k-graphs

Iain Raeburn

University of Otago

Date: Thursday 6 November 2014

141116140158
Categorical notion of k-graphs

Iain Raeburn

University of Otago

Date: Thursday 30 October 2014

141102123014
Quantum Heisenberg manifolds as twisted groupoid C*-algebras

Sooran Kang

University of Otago

Date: Thursday 23 October 2014

141023135510
The structure of quantum Heisenberg manifolds III

Sooran Kang

University of Otago

Date: Thursday 16 October 2014

141016135248
The structure of quantum Heisenberg manifolds II

Sooran Kang

University of Otago

Date: Thursday 2 October 2014

141002143545
The structure of quantum Heisenberg manifolds I

Sooran Kang

University of Otago

Date: Thursday 25 September 2014

141002143403
Picard group and symmetric Hilbert C*-bimodules

Sooran Kang

University of Otago

Date: Thursday 18 September 2014

140921160933
Realization of crossed products by Hilbert C*-bimodules as Cuntz-Pimsner algebras II

Sooran Kang

University of Otago

Date: Thursday 11 September 2014

140910145348
Realization of crossed products by Hilbert C*-bimodules as Cuntz-Pimsner algebras I

Sooran Kang

University of Otago

Date: Thursday 4 September 2014

140910145215
Quasi-lattice ordered groups and their C*-algebras II

Ilija Tolich

University of Otago

Date: Thursday 24 July 2014

140723162558
Quasi-lattice ordered groups and their C*-algebras I

Ilija Tolich

University of Otago

Date: Thursday 17 July 2014

140717140332
Spatial realization of KMS_beta states on C*-algebras associated to a finite k-graph

Sooran Kang


Date: Thursday 26 September 2013

130925164549
KMS states for generalised gauge actions II

Richard McNamara


Date: Thursday 19 September 2013

130925164729
KMS states for generalised gauge actions

Richard McNamara


Date: Thursday 12 September 2013

130911145822
KMS states of Toeplitz algebras II

Zahra Afsar


Date: Thursday 5 September 2013

130904140832
KMS states of Toeplitz algebras

Zahra Afsar


Date: Thursday 22 August 2013

130820154844
Power partial isometries III

Ilija Tolich


Date: Thursday 15 August 2013

130808144146
Power partial isometries II

Ilija Tolich


Date: Thursday 8 August 2013

130808104238
Power partial isometries

Ilija Tolich


Date: Thursday 1 August 2013

130808105053
Purely infinite simple groupoid algebras II

Lisa Orloff Clark


Date: Thursday 25 July 2013

130808105215
Purely infinite simple groupoid algebras

Lisa Orloff Clark


Date: Thursday 18 July 2013

130808144510
Quasidiagonal C*-algebras II

Astrid an Huef


Date: Friday 5 July 2013

130808144824
Quasidiagonal C*-algebras

Astrid an Huef


Date: Thursday 27 June 2013

130808144947
Fell Bundles and Gradings IV

Iain Raeburn


Date: Friday 17 May 2013

130808145305
Fell Bundles and Gradings III

Iain Raeburn


Date: Friday 10 May 2013

130808145757
Fell Bundles and Gradings II

Iain Raeburn


Date: Friday 3 May 2013

130808145824
Fell Bundles and Gradings

Iain Raeburn


Date: Friday 26 April 2013

130808145947
Textile system and its applications II

Sooran Kang


Date: Friday 12 April 2013

130808144406
Textile system and its applications

Sooran Kang


Date: Thursday 4 April 2013

130808144225
New C*-completions of discrete groups IV

Astrid an Huef


Date: Friday 22 March 2013

130808150839
New C*-completions of discrete groups III

Astrid an Huef


Date: Friday 15 March 2013

130808150813
New C*-completions of discrete groups II

Astrid an Huef


Date: Friday 8 March 2013

130808150537
New C*-completions of discrete groups

Astrid an Huef


Date: Friday 1 March 2013

130808150030
Simplicity of groupoid C*-algebras

Jon Brown

University of Otago

Date: Thursday 12 July 2012

120711105914
Gelfand-Kirillov dimension of Leavitt path algebras

John Clark

University of Otago

Date: Thursday 5 July 2012

120702122013
Groupoids and Baire Category Theorem

Lisa Orloff Clark

University of Otago

Date: Friday 29 June 2012

120627165240