Messages

Published Apr. 7, 2026 1:03 PM

Dear all,

The lecture on April 10 will instead take place on April 9 at 10:15 in NHA720.

Best,

Ulrik

Published Mar. 19, 2026 9:56 AM

Dear all,

Sorrily the lecture tomorrow on Friday March 20 has to be canceled.

Also, the lecture on Monday March 23 will be rescheduled to Tuesday March 24, in room 720 of Niels Henrik Abels Hus.

Sorry for the hassle!

Ulrik

Published Feb. 27, 2026 2:28 PM

Hi all,

In week 10 (March 2-6), I will have to reschedule the two lectures. They will be on Monday at 10:15 and Tuesday at 14:15.

Ulrik

Published Feb. 26, 2026 12:07 PM

Hi all,

Tomorrow's lecture on Friday February 27 is canceled.

Ulrik

Published Jan. 19, 2026 4:26 PM

Due to a PhD defense on January 23, we will instead have the lecture the day before, on Thursday January 22 in room 720 in Niels Henrik Abels Hus at 14:15. If this time is inconvenient, please contact me.

Published Jan. 15, 2026 1:47 PM

I will base the lecture notes on material from the following books:

  • Dana Williams: A toolkit for groupoid C*-algebras
  • Claire Anantharaman-Delaroche and Jean Renault: Amenable groupoids
  • Alan L. T. Paterson: Groupoids, Inverse Semigroups and their Operator Algebras
  • Aidan Sims: Lecture notes on étale groupoids and their C*-algebras
Published Jan. 7, 2026 2:28 PM

The theme of MAT9390 this spring will be groupoids and their operator algebras. I plan to focus on topological groupoids and their C*-algebras, but hopefully also cover some aspects of measured groupoids and their von Neumann algebras.

The topics I plan on covering, or at least touch upon, are the following:

  • Unitary representation theory of groupoids
  • Equivalence of groupoids
  • Amenability of groupoids
  • Kumjian-Renault theory for twisted groupoids and Cartan subalgebras

I will publish lecture notes as the lectures progress.

The set lecture times are Mondays 14:15-16:00 and Fridays 10:15-12:00 in room NHA1020, with the first lecture being on Monday January 19th.

Published Dec. 9, 2025 10:32 AM

Welcome to the webpage of MAT9390! The topic this time will be groupoids and their C*-algebras. If you want to follow the course, do not hesitate to contact me. You are welcome to do so regardless of whether you plan to take the exam.

Ulrik