Masterclass on Ergodic Theory and von Neumann algebras

The University of Copenhagen

October 14-18, 2013


In the last ten years impressive work has been done at the interface between ergodic theory and von Neumann algebras. The purpose of this PhD course is to present – in the two main lecture series by Damien Gaboriau and Cyril Houdayer – the ergodic theory part and the von Neumann algebra side of this newly developed machinery. Steven Deprez will give supplementary lectures on von Neumann algebras.

On the occasion that the Kadison-Singer problem very recently has been solved by Adam Marcus, Daniel Spielman and Nikhil Srivastava, a part of the Masterclass is devoted to a presentation of this problem. Pete Casazza will give a lecture series. In addition, Ilijas Farah will give a lecture on the (other) Kadison-Singer problem, answered in the negative by Akemann and Weaver in 2008 (assuming the continuum hypothesis).


The main lecture series will be delivered by:

In addition there will be lectures by

Titles and abstracts:

  • Pete Casazza: The Kadison-Singer Problem in Mathematics and Engineering
  • Steven Deprez: Introduction to the link between von Neumann algebras and ergodic theory
  • Ilijas Farah: The other Kadison-Singer Problem
  • Damien Gaboriau: Around the orbit equivalence theory of the free groups
  • Cyril Houdayer: Von Neumann algebras with unique Cartan decomposition

Click HERE for abstracts.

Slides for Pete Casazza's lectures:

Notes for the lectures:


The lectures will be held at the Department of Mathematical Sciences at the University of Copenhagen, and the event is hosted by the Centre for Symmetry and Deformation. You can find information for short term visitors including directions to the mathematics department HERE


We recommend Hotel de 9 Små Hjem, which is pleasant and inexpensive and offers room with a kitchen. Other inexpensive alternatives are CabInn that has several locations in Copenhagen: the Hotel City (close to Tivoli), Hotel Scandivania (Frederiksberg, close to the lakes), and Hotel Express (Frederiksberg) are the most convenient locations; the latter two are 2.5-3 km from the math department.

Somewhat more expensive - and still recommended - options are Hotel Nora and Ibsen's Hotel. Invited speakers need not reserve hotel rooms (this will be taken care of by the organizers). 


Participants can apply for support to partly cover their living costs while attending the masterclass. The support will be DKK 500 per day, and it will primarily be given to participating PhD students and postdocs. Please indicate on the registration form if you wish to be considered for this support. In this case you must also send your cv and a brief motivation for your participation in the masterclass to Steven Deprez (Email:

Deadline for application for support has expired.


Please register for the Masterclass by filling in this registration form.  Registration is free. 

Deadline for registration has expired.


Program can be found HERE.


List of participants can be found HERE.

Organizers: Magdalena Musat, Steven Deprez, Mikael Rørdam, Kristian Olesen, Søren Knudby.