# Talks by Stefaan Vaes

## Invited conference talks, lecture series and colloquia by Stefaan Vaes

### 2024

23 - 27 Sep Group Operator Algebras: Classification, Structure and Rigidity. Banff International Research Station (BIRS), Banff, Canada

17 - 20 Jun Noncommutativity in the North – MikaelFest, Chalmers University of Technology and University of Gothenburg, Gothenburg, Sweden.

22 - 26 Apr Group operator algebras and non commutative geometry, Centre International des Rencontres Mathématiques (CIRM), Marseille, France.

26 - 27 Feb Noncommutative Geometry, Analysis on Groups, and Mathematical Physics, Universiteit Gent.

### 2023

6 - 10 Nov Twinned Conference on C*-Algebras and Tensor Categories, International Centre for Mathematical Sciences, Edinburgh, United Kingdom.

9 - 13 Oct Totally disconnected locally compact groups: local to global, Münster, Germany.

21 - 25 Aug Conference on noncommutative harmonic analysis and rigidity theory in operator algebras, TU Delft, Delft, The Netherlands.

26 - 30 Jun Operator Algebras: Subfactors and Applications, Isaac Newton Institute, Cambridge, United Kingdom.

22 - 26 May Quantum groups and interactions, Glasgow, United Kingdom.

25 - 29 Mar Modern Trends in Operator Algebras, in memory of Ed Effros, UCLA, Los Angeles, United States.

### 2022

22 Sep Joint Mathematics Colloquium, ICMAT-UAM-UC3M-UCM, Madrid, Spain.

12 - 16 Sep Noncommutative harmonic analysis and quantum groups, Polish Academy of Sciences, Bedlewo, Poland.

29 Aug-2 Sep Von Neumann algebras, Hausdorff Research Institute for Mathematics, Bonn, Germany.

1 - 4 Jul Operator algebras, dynamics and groups, ICM satellite conference, Copenhagen, Denmark.

30 May-3 Jun Plenary lecture at the 50th Canadian Operator Algebra Symposium (COSy), Ottawa, Canada.

24 - 28 May Lecture series at the workshop Topological quantum groups, C*-tensor categories, and subfactors, University of Waterloo, Canada.

16 - 20 May Operator Algebras and Group Dynamics, Centre International des Rencontres Mathématiques (CIRM), Marseille, France.

31 Mar Mathematics Colloquium, University of Nevada at Reno, United States. (online)

11 Feb Distinguished Lecture of the Pacific Institute of Mathematical Sciences, University of Regina, Canada. (online)

### 2021

18 - 21 Oct Automorphisms and Invariants of Operator Algebras, Copenhagen University, Denmark.

13 - 17 Sep Quantum Groups: Algebra, Analysis and Category Theory, Oberwolfach, Germany.

23 - 27 Aug Noncommutative harmonic analysis and quantum groups, Będlewo, Poland. (postponed due to COVID-19 pandemic)

9 - 13 Aug Plenary lecture at the International Workshop on Operator Theory and its Applications (IWOTA), Orange, United States. (online)

20 - 21 Mar Brazos Analysis Seminar, Texas, United States. (online)

25 - 29 Jan Mini-course at the workshop Actions of Tensor Categories on C*-algebras, IPAM, UCLA, Los Angeles, United States. (online)

### 2020

13 - 18 Dec IPAM's Quantitative Linear Algebra Reunion Conference II, IPAM, Lake Arrowhead, San Bernardino County, United States. (postponed due to COVID-19 pandemic)

11 Dec Meeting of the Edinburgh Mathematical Society, Glasgow, United Kingdom. (online)

10 - 13 Dec Operator algebras, quantum information and beyond, UCLA, Los Angeles, United States. (postponed due to COVID-19 pandemic)

12 - 15 Oct Automorphisms and Invariants of Operator Algebras, Copenhagen University, Denmark. (postponed due to COVID-19 pandemic)

18 - 20 Aug Noncommutative Conference, Ghent Analysis and PDE Center, Gent, Belgium. (online)

27 - 31 Jul Mini-course at the concentration week Topological quantum groups, C*-tensor categories, and subfactors, Texas A&M University, College Station, United States. (postponed due to COVID-19 pandemic)

15 - 19 Jun Fifty years of Tomita-Takesaki theory, Tokyo University, Tokyo, Japan. (postponed due to COVID-19 pandemic)

21 Apr Polish Analysis Seminar, Institute of Mathematics of the Polish Academy of Science, Warsaw, Poland. (postponed due to COVID-19 pandemic)

30 Mar-3 Apr Deligne categories and quantum groups, RWTH Aachen University, Germany. (postponed due to COVID-19 pandemic)

21 - 22 Mar Workshop on II_1 factors, UCLA, Los Angeles, United States. (postponed due to COVID-19 pandemic)

### 2019

29 - 30 Nov Memorial conference Richard V. Kadison, Carlsberg Academy, Copenhagen, Denmark.

Oct 31 Bourgain Day, Vrije Universiteit Brussel, Belgium.

Sep 29-Oct 4 Classification problems in von Neumann algebras, Banff International Research Station, Banff, Canada.

Sep 1 - 14 Chern lectures, Yau Mathematical Sciences Center, Tsinghua University, Beijing, China.

Jun 20 - 22 Opening Colloquium Excellence cluster Mathematics, WWU Münster University, Münster, Germany.

May 21 - 24 Conference Groupoids and Operator Algebras in honor of Jean Renault, Orléans University, Orléans, France.

May 9 Lecture at the Leçons de Mathématiques et d'Informatique d'aujourd'hui, Bordeaux, France.

Apr 29-May 3 Masterclass Subfactors and quantum groups, Department of Mathematics, University of Copenhagen, Denmark.

Apr 8-12 Conference in honor of Étienne Blanchard, Institut de Mathématiques de Jussieu, Université Paris Diderot, Paris, France.

Mar 11-15 Lecture series at Operator Algebras, Groups and Applications to Quantum Information, ICMAT, Madrid, Spain.

### 2018

Dec 17-18 Symposium in honor of Alain Valette's 60th birthday, Neuchâtel, Switzerland.

Nov 26-30 Workshop Model theory and operator algebras, Banff International Research Station, Banff, Canada.

Jun 4-8 Plenary lecture SMF 2018: congrès de la Société Mathématique de France, Lille, France.

Jun 4-8 Workshop L^2-invariants, ICMAT, Madrid, Spain.

Apr 30-May 5 Workshop Approximation properties in operator algebras and ergodic theory, Institute of Pure and Applied Mathematics, UCLA, Los Angeles, United States.

Apr 19 Institute of Mathematics Colloquium, EPFL, Lausanne, Switzerland.

Mar 15 Colloquium, Institute of Mathematics of Jussieu, Paris, France.

Mar 5-6 Tensor categories and analysis, Laboratoire de Mathématiques Nicolas Oresme, Caen, France.

### 2017

Nov 30-Dec 1 Plenary lecture at Arbre de Noël, Orsay University, Orsay, France.

Oct 13-14 Meeting in honor of Saad Baaj, University Clermont-Auvergne, Clermont-Ferrand, France.

Oct 2 Colloquium School of Mathematical Sciences, Queen Mary University, London, United Kingdom.

Sep 27-29 Plenary lecture at Joint meeting of the Edinburgh Mathematical Society and Societat Catalana de Matemàtiques, Edinburgh University, Edinburgh, United Kingdom.

Sep 18-22 Two lectures at the workshop MASAs and Automorphisms of C*-Algebras, Oberwolfach, Germany.

Aug 23-25 Opening lecture of the 43th Conference of the Belgian Society of French speaking Mathematics Teachers, Liège, Belgium.

June 12 Rotschild Lecture, Isaac Newton Institute, Cambridge, United Kingdom.

May 8-12 Approximation, deformation, quasification, Isaac Newton Institute, Cambridge, United Kingdom.

Mar 29 - Apr 2 Noncommutative geometry: state of the art and future prospects, Fudan Institute for Advanced Study, Fudan University, Shanghai, China.

Mar 31 Spring Operator Algebras Program, Research Center for Operator Algebras, East China National University, Shanghai, China.

Jan 23-27 Structure of Operator Algebras: Subfactors and Fusion Categories, Isaac Newton Institute, Cambridge, United Kingdom.

Jan 16-20 Lecture series at Primer on Subfactors and Applications, Isaac Newton Institute, Cambridge, United Kingdom.

### 2016

Dec 13-17 Lecture series at Recent Advances in Operator Theory and Operator Algebras, Indian Statistical Institute, Bangalore, India.

Dec 9 ULB Mathematics Colloquium, ULB, Brussels, Belgium.

Oct 4-7 Riemann Conference, Münster University, Münster, Germany.

Aug 8-12 Conference Operator Algebras and Mathematical Physics, Tohoku University, Sendai, Japan.

Jul 18-22 7th European Congress of Mathematics, invited lecture, TU Berlin, Berlin, Germany.

Jun 24-26 Symposium The mathematical legacy of Uffe Haagerup, University of Copenhagen, Denmark.

May 17-25 Lecture series at the NCGOA Spring Institute 2016, Hausdorff Institute for Mathematics, Bonn, Germany.

May 13 Young Mathematicians Colloquium, Lille, France.

Apr 18-22 Workshop Von Neumann Algebras, Mittag-Leffler Institute, Stockholm, Sweden.

Mar 22-23 Plenary lecture at the BeNeLux Mathematical Congress, UvA, Amsterdam, The Netherlands.

Feb 22 Inaugural lecture Francqui Chair, VUB, Brussels, Belgium.

### 2015

Nov 2-6 Noncommutative Geometry, Centre International des Rencontres Mathématiques, Marseille, France. Video recording.

Aug 17-21 Lecture series at the YMC*A, Young Mathematicians in C*-Algebras, University of Copenhagen, Denmark.

Aug 7-11 Abel Symposium, Hurtigruten Bergen-Harstad, Norway.

Jun 22-23 Scottish Operator Algebra Seminar, Aberdeen, United Kingdom.

Jun 1-3 Focus programme C*-algebras, Münster, Germany.

May 1-17 NCGOA 13 Operator Algebras and Approximation Properties of Groups, Vanderbilt University, Nashville, USA.

Mar 24-28 Workshop Subfactors and Conformal Field Theory, Oberwolfach, Germany.

Mar 9-13 Workshop Kadison-Singer, Interlacing Polynomials, and Beyond, MSRI, Berkeley, USA.

### 2014

Nov 27-29 Meeting of the GDR Noncommutative Geometry, Besançon, France.

Oct 23 Colloquium Institute of Mathematics, UC Louvain, Louvain-la-Neuve, Belgium.

Sep 22-26 Workshop Von Neumann Algebras and Ergodic Theory, UCLA, Los Angeles, USA.

Aug 8-12 ICM Satellite Meeting Operator algebras and applications, plenary lecture, Cheong Pung, Jecheon, Korea.

Jun 30-Jul 5 OT25: 25th International Conference in Operator Theory, Timisoara, Romania.

Jun 2-6 Discrete groups and geometric structures, with applications, V, Leuven, Belgium.

Apr 1-3 Belgian Bracket and Quantization Workshop, Brussels, Belgium.

### 2013

Oct 31 General Mathematics Colloquium, Utrecht, The Netherlands.

Oct 28-31 Nord Pas de Calais/Belgium congress of mathematics, Valenciennes-Mons, France-Belgium.

Oct 24 Colloquium Mathematische Gesellschaft, Göttingen, Germany.

Aug 26-30 Conference C*-algebras, Oberwolfach, Germany.

Jul 8-12 Conference Mathematics and Quantum Physics, plenary lecture, Accademia dei Lincei, Rome, Italy.

Jun 24-28 Summer School Rigidity and Group Actions, lecture series, Institut de Mathématiques de Jussieu, Paris, France.

May 30-31 Conference Geometry and Analysis on groups , Neuchâtel, Switzerland.

May 20-24 Research program Operator Algebras and Harmonic Analysis, lecture series, ICMAT, Madrid, Spain.

Mar 7 Mathematics Colloquium, University of California at San Diego, UCSD, United States.

Jan 18 Colloquium Department of Mathematics, Saarland University, Saarbrücken, Germany.

### 2012

Dec 19-22 Winter School Banach Spaces and Operator Algebras, lecture series, Cheong Pung Resort, Jecheon, Korea.

Sep 24-28 Kick-off conference Centre Européen pour les Mathématiques, la Physique et leurs Interactions, plenary lecture, University of Lille, Lille, France.

Jun 18 - 22 Descriptive set theory and functional analysis, BIRS, Banff, Canada.

June 6-8 Joint Conference of the Belgian, Royal Spanish and Luxembourg Mathematical Societies, plenary lecture, University of Liège, Liège, Belgium.

May 30-Jun 3 GPOTS 2012, plenary lecture, University of Houston, Houston, United States.

Mar 21 - 22 Operator algebras, Quantum groups and Tensor categories, in honor of L. Vainerman, Caen, France.

Jan 9 - 13 Conference on von Neumann Algebras and Related Topics, RIMS, Kyoto University, Japan.

### 2011

Dec 7 - 16 Winter School on Operator Algebras, RIMS, Kyoto University, Japan. Lecture series.

Sep 21 - 23 Workshop for young researchers in mathematics 2011, Universidad Complutense de Madrid, Madrid, Spain.

Sep 19 - 23 Operator algebras and quantum groups, Stefan Banach Center for Mathematics, Warsaw, Poland.

May 31 Colloquium, University of Metz, France.

May 2 - 20 Von Neumann algebras and ergodic theory of group actions, IHP, Paris, France.

Apr 25 - 30 Annual Meeting EU-NCG, IMAR, Bucharest, Romania.

### 2010

Oct 9 - 10 AMS Western Section Meeting, UCLA, Los Angeles, United States.

Aug 19 - 27 International Congress of Mathematicians, invited lecture in the section Functional Analysis and Applications, Hyderabad, India.

May 10 - 19 Eighth annual spring institute on noncommutative geometry and operator algebras, Vanderbilt University, Nashville, United States.

Mar 7 - 13 Conference C*-Algebras, Oberwolfach, Germany.

Feb 1 - 5 Workshop on von Neumann algebras and group actions, University of Copenhagen, Denmark.

### 2009

Dec 8 - 11 Operators and Operator Algebras in honour of A. Gillespie and A. Sinclair, The University of Edinburgh, United Kingdom.

Dec 7 - 11 Operator algebras, groups and geometry, CIRM, Marseille, France.

Sep 28-Oct 2 Annual meeting of EU-network Noncommutative Geometry, University of Copenhagen, Denmark.

Sep 16 - 18 Lecture series at the School on Operator Algebras, Institute of Mathematics of the Romanian Academy, Bucharest, Romania.

Jul 14 - 24 Banach Algebras 2009, Stefan Banach International Mathematical Center, Będlewo, Poland.

May 14 - 16 Workshop Quantum Groups, Université Paul Sabatier, Toulouse, France.

Mar 15 - 18 Workshop Von Neumann algebras and ergodic theory, UCLA, Los Angeles, United States.

Mar 4 Mathematics Colloquium, Radboud University, Nijmegen, The Netherlands.

Feb 12 Colloquium de Mathématiques Pures et Appliquées, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.

Feb 5 Mathematics Colloquium, University of Münster, Germany.

### 2008

Dec 4 - 6 Journées groupes et algèbres d'opérateurs, Université de Caen, France.

Oct 26-Nov 1 Von Neumann algebras and ergodic theory of group actions, Mathematisches Forschungsinstitut Oberwolfach, Germany.

Aug 17 - 23 C*-algebras, Mathematisches Forschungsinstitut Oberwolfach, Germany.

Jun 27 - 28 Operator Algebra Days, at the occasion of the retirement of Claire Anantharaman-Delaroche, Bourges, France.

Jun 13 Meeting of the Tripode, Lyon, France.

Mar 23 - 28 Topics in von Neumann algebras, Banff, Canada.

### 2007

Dec 11 - 15 Fields Institute Workshop Operator Spaces and Quantum Groups, Toronto, Canada.

Nov 23 - 25 Inaugural meeting of the GDRE Non Commutative Geometry, Rome, Italy.

Nov 2 - 3 North British Functional Analysis Seminar, Leeds, United Kingdom.

Oct 29-Nov 2 Fields Institute Workshop Von Neumann Algebras, Toronto, Canada.

Aug 13 - 24 Summer School Operator Algebras, Ottawa, Canada.

Jun 18 - 22 Meeting of the GDR Noncommutative Geometry, Fleurance, France.

Mar 29-Apr 6 Non Commutative Geometry, Conference in honor of Alain Connes, IHP, Paris, France.

Mar 17 - 19 Workshop Von Neumann algebras and ergodic theory, UCLA, Los Angeles, United-States.

Feb 26-Mar 2 Conference Groupoids in operator algebras and noncommutative geometry, IHP, Paris, France.

### 2006

Nov 15 - 18 MSJ-IHES Joint Workshop on Noncommutativity, IHES, Bures-sur-Yvette, France.

Nov 8 - 11 Workshop Recent advances in operator algebras, Rome, Italy.

Sep 21 - 28 Research group Noncommutative Geometry and Operator Algebras, Vanderbilt University, United States. Title: Deformation and rigidity results for crossed product II_1 factors.

Sep 16 - 21 Topics in von Neumann algebras, Banff, Canada.

Jun 6 - 9 Symposion of the Sonderforschungsbereich Geometrische Stukturen in der Mathematik, Münster, Germany.

May 27 - 30 Beyond Amenability: Groups, Actions and Operator Algebras, UCLA, Los Angeles, United States.

Mar 19 Bourbaki Seminar, Rigidity results for Bernoulli shifts and their von Neumann algebras (after Sorin Popa), Institut Henri Poincaré, Paris, France.

### 2005

Lecture series at the PhD School of the Center in Non-Commutative Geometry, Copenhagen, Denmark.

C*-Algebren, Oberwolfach, Germany.

Operator Algebras and Mathematical Physics, Bucharest, Romania.

Fields Institute Summer School Operator Algebras, Ottawa, Canada.

Joint meeting Benelux - France, Gent, Belgium.

Cours Peccot in the Collège de France, Paris.

### 2004

Colloquium, Institute of Mathematics, University of Neuchâtel, Switzerland.

Non-commutative geometry, Oberwolfach, Germany.

Fields Institute Workshop on Kazhdan's Property (T), Ottawa, Canada.

K-theory and non-commutative geometry, Institut Henri Poincaré, Paris, France.

Bourbaki Seminar, Free quasi-free states and factors of type III (after D. Shlyakhtenko), Institut Henri Poincaré, Paris, France.

Locally compact quantum groups and quantum symmetries, CIRM, Marseille, France.

Non-commutative geometry 2004 von Neumann algebras, CIRM, Marseille, France.

### 2003

C*-Algebren, Mathematisches Forschungsinstitut Oberwolfach, Germany.

International Conference "Groups", Paris, France.

### 2002

Frontier of Non Commutative Analysis and Mathematical Quantum Theory, Kyushu University, Fukuoka, Japan.

9th Leuven Mathematical Physics Days, K.U.Leuven, Belgium.

Nichtkommutative Geometrie, Mathematisches Forschungsinstitut Oberwolfach, Germany.

69th Rencontre entre Physiciens et Mathématiciens, Strasbourg, France.

### 2001

School/Conference on noncommutative geometry and quantum groups, Warsaw, Poland.

Colloquium Pure Mathematics, Department of Mathematics, Queen's University Belfast, United Kingdom.

Workshop on quantum groups and special functions, T.U.Delft, The Netherlands.

### 2000

XIIIth International Conference on Mathematical Physics, London, United Kingdom.

Workshop Mathematical and Physical Aspects of Quantum groups organized by the Max-Planck Institutes of Munich and Leipzig in Bayrischzell, Germany.

### 1999

Colloquium of the Institute Korteweg-de-Vries of Mathematics of the University of Amsterdam, the Netherlands.

Analysis and deformed algebras, University of Antwerp, Belgium.

## Recent seminar talks

29/05/2024 Operator Algebra Seminar, Mathematics Department, University of Rome Tor Vergata, Rome, Italy.

15/02/2024 Operator Algebra Seminar, Jussieu Mathematics Institute, Paris, France.

22/11/2022 Quantum Groups Seminar (online).

05/10/2022 Functional Analysis Seminar, UCLA, United States. (online)

13/05/2022 Operator Algebra Seminar, KU Leuven, Belgium.

06/05/2022 Functional Analysis and Operator Algebras in Athens, Greece. (online)

27/10/2021 Functional Analysis Seminar, UCLA, United States. (online)

06/10/2021 Global Noncommutative Geometry Seminar. (online)

02/06/2021 Functional Analysis Seminar, UCLA, United States. (online)

02/02/2021 Mathematical Picture Language Seminar, Harvard University, Cambridge, MA, United States. (online)

28/01/2021 Seminar Operator Algebras, Jussieu Mathematics Institute, Paris, France. (online)

## Talks for a wider audience

6-7 Sep 2024 Mini-course for secundary school mathematics teachers: The Banach-Tarski Paradox, Antwerp. Lecture notes. Slides. Introduction to group theory by Jeroen Spandaw.

23-24 Aug 2024 Mini-course for secundary school mathematics teachers: The Banach-Tarski Paradox, Amsterdam, The Netherlands. Lecture notes. Slides. Introduction to group theory by Jeroen Spandaw.

14/12/2023 TRansformers: From Algebra to AI. ARhus, Roeselare.

22/09/2023 Talk at the Mathematics Tournament at KU Leuven.

17/09/2023 Talk at MathFest, a mathematics festival organized by Platform Wiskunde Vlaanderen, Brugge.

06/03/2023 Science@Leuven event at the IMAGINARY exhibition; lecture: Alhambra - Penrose - einstein.

10/01/2023 Lecture at the Junior College Day in Leuven: Dobble, how to earn points with lines and planes.

24/09/2021 Lecture at the celebration of 10 years Platform Wiskunde Nederland, Spectral gap: from the surface area of a sphere to operator algebras, Amsterdam, Netherlands.

28/01/2020 Lecture at service club Fifty-One, Aarschot, Belgium.

16/05/2017 Frontiers Lecture at The Learned Society of Wales, Cardiff, United Kingdom.

26/04/2017 Lecture at the Science Days of Don Bosco secondary school, Haacht, Belgium.

15/03/2017 Lecture at the prize ceremony of Wiskunde B-dag, Leuven, Belgium.

15/03/2016 Student association WINA, Leuven, Belgium.

17/02/2016 Science Night, KULAK, Kortrijk, Belgium.

03/12/2015 Mathematics for everybody, Davidsfonds, Herentals, Belgium.

26/11/2015 Wir müssen wissen, wir werden wissen, lecture at Metaforum, KU Leuven, Belgium.

14/10/2015 Wir müssen wissen, wir werden wissen, lecture at the Royal Flemish Academy of Belgium for Science and the Arts, Brussels, Belgium.

09/10/2015 Lecture Mathematics of the XXI century, Leuven, Belgium.

23/09/2015 Public debate Science is wonder-ful, 10th anniversary of the European Researchers' Night, Brussels, Belgium.

22/09/2015 Opening speech of the academic year 2015-2016, KULAK, Kortrijk, Belgium.

13/03/2014 Mad Math Day, Sint-Victorinstituut, Turnhout, Belgium.

11/2011 The Banach Tarski paradox, PRIME, UGent, Belgium.

02/2011 Homer Simpson discovers mathematics, Department of Mathematics, K.U.Leuven, Belgium.

02/2009 How easily you can win the next Nobel prize in mathematics, Department of Mathematics, K.U.Leuven, Belgium.

10/2007 Conférence à la Sociéte Royale des Sciences de Liège Faire deux oranges à partir d'une : les mathématiques mènent-elles à des paradoxes?, Liège, Belgium.

05/2004 Talk at the proclamation of the Flemish Mathematics Olympiad How Gödel astonished mathematics, University of Gent, Belgium.

03/2004 Popularizing talk on A-periodic tilings of the plane and the golden ratio, Department of Mathematics, K.U.Leuven, Belgium.

10/2002 Lecture at the Robert Stock Prize ceremony, K.U.Leuven, Belgium.