Topological Hochschild Homology and Zeta Values

Masterclass - University of Copenhagen
30 January - 3 February 2023

The masterclass will present spectacular recent advances in motivic filtrations and their applications. To briefly put this in context, every cohomology theory, in arithmetic geometry and elsewhere, should arise as the graded pieces of a motivic filtration of some localizing invariant, algebraic K-theory and topological cyclic homology being notable examples. The definition of the appropriate motivic filtrations, however, was long elusive. Voevodsky received the 2002 Fields medal, in part, for his definition of the motivic filtration of algebraic K-theory of schemes smooth over a field. This definition, however, was based on algebraic cycles, which are notoriously difficult to handle. In 2018, Bhatt, Morrow, and Scholze defined a motivic filtration of p-complete topological cyclic homology in an entirely different way, which is much simpler and easier to employ elsewhere, and this breakthrough has led to numerous advances.

Building on work of Antieau, Morin, and, independently, Bhatt-Lurie, have refined the Bhatt-Morrow-Scholze filtration to a filtration of non-completed topological cyclic homology, and Morin discovered that its graded pieces precisely account for an archimedean factor in a conjectural formula for the special values of the Hasse-Weil zeta function of a regular scheme, proper over the integers. It is very exciting to see that such quantative archimedean information can be extracted from topological cyclic homology! More recently, Hahn-Raksit-Wilson introduced the even filtration, and showed that it accounts for both the Bhatt-Morrow-Scholze filtration and the Morin and Bhatt-Lurie refinements thereof. It might also recover and extend Voevodsky's filtration?



  • Benjamin Antieau (Northwestern University)
  • Achim Krause (WWU Münster)
  • Matthias Flach (Caltech)










Monday Tuesday Wednesday Thursday Friday
9:00-9:30 Registration
09:30-10:30 Antieau 1
09:30-10:30 Flach 2
09:30-10:30 Antieau 4
09:30-10:30 Krause 4
09:30-10:30 Flach 5
10:30-11:30 Questions and tea
10:30-11:30 Questions and tea
10:30-11:30 Questions and tea
10:30-11:30 Questions and tea
10:30-11:30 Questions and tea
11:30-12:30 Flach 1 11:30-12:30 Krause 2 11:30-12:30 Flach 3 11:30-12:30 Flach 4 11:30-12:30 Krause 5
12:30-14:30 Lunch 12:30-14:30 Lunch
12:30-14:30 Lunch
12:30-14:30 Lunch
12:30-14:30 Lunch
14:30-15:30 Krause 1 14:30-15:30 Antieau 3
14:30-15:30 Antieau 5
15:30-16:30 Questions and tea 15:30-16:30 Questions and tea
15:30-16:30 Questions and tea
16:30-17:30 Antieau 2 16:30-17:30 Krause 3 16:30-17:30 TBD
17:30: Pizza & Drinks reception 18:00: Dinner at Food Club










The conference/masterclass will take place at the Department of Mathematical Sciences, University of Copenhagen. See detailed instructions on how to reach Copenhagen and the conference venue.

Tickets and passes for public transportation can be bought at the Copenhagen Airport and every train or metro station. You can find the DSB ticket office on your right-hand side as soon as you come out of the arrival area of the airport. DSB has an agreement with 7-Eleven, so many of their shops double as selling points for public transportation.

A journey planner in English is available.

More information on the "find us" webpage.







We kindly ask the participants to arrange their own accommodation.

We recommend Hotel 9 Små Hjem, which is pleasant and inexpensive and offers rooms with a kitchen. Other inexpensive alternatives are CabInn, which 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.

An additional option is to combine a stay at the CabInn Metro Hotel with a pass for Copenhagen public transportation (efficient and reliable). See information about tickets & prices.













Registration is free. Participants will get free lunches, coffee/tea etc, an opening reception and conference dinner.

Registration is closed. Please contact Mikala: if you have any questions.


Participants, who do not have access to funding for travel and accommodation, can apply for a reimbursement of up to DKK 2,500 for travel and accommodation.


Deadline for applying is 15th of January 2023.