Embedded Files
Our seminar runs on Tuesdays from 13:00 to 14:00. Contact:
09/09/2025: Robert-Mihai Neagu (KU Leuven), at 13:00 in the CP3 meeting room.
Title: Noncommutative coloured entropy
Abstract: Building on the classical noncommutative entropy for automorphisms of nuclear C*-algebras, I will introduce a formally different notion of entropy which uses the more refined cpc approximations given by finite nuclear dimension or finite decomposition rank. In the sequel, I will explore the typical values of this entropy. This is joint work with Bhishan Jacelon.
16/09/2025: Villads Ussing Bojesen (SDU), at 13:00 in the IMADA seminar room.
Title: The (Local) Lifting Problem for C*-Algebras
Abstract: A C*-algebra is said to have the Lifting Property (LP) if every completely positive map into a quotient C*-algebra has a completely positive lift. Through the years, the LP and its local version, the LLP, have been getting a lot of traction both because of their usefulness, but also their relevance in connecting various major problems such as Kirchberg's QWEP-conjecture, Connes' Embedding Problem and Tsirelson's Problem. I will introduce these properties and study the problem of finding groups whose full group C*-algebras fail the LLP. I will present a class of examples due to Ioana, Spaas and Wiersma which in particular include SL3(Z).
The seminar is based on my master's thesis: “Lifting Properties of Group C*-Algebras and Operator Spaces.”
30/09/2025: David Jekel (Københavns Universitet), at 13:00 in U177.
Title: The unitary group of a II_1 factor is SOT-contractible
Abstract: I show that the unitary group of any SOT-separable II_1 factor M, with the strong operator topology, is contractible. Combined with several old results, this implies that the same is true for any SOT-separable von Neumann algebra with no type I_n direct summands (n < infinity). The proof for the II_1-factor case uses regularization via free convolution and Popa's theorem on the existence of approximately free Haar unitaries in II_1 factors. I will also explain some of the bigger picture of the free probability ingredients.
07/10/2025: Jamie Bell (University of Münster), at 13:00 in U166.
Title: TBA
Abstract: TBA
21/10/2025: TBA, at 13:00 in U163.
Title: TBA
Abstract: TBA
28/10/2025: TBA, at 13:00 in U183.
Title: TBA
Abstract: TBA
04/11/2025: TBA, at 13:00 in U166.
Title: TBA
Abstract: TBA
11/11/2025: TBA, at 13:00 in U163.
Title: TBA
Abstract: TBA
18/11/2025: Rufus Willett (University of Hawai'i at Mānoa), at 13:00 in U168.
Title: TBA
Abstract: TBA
25/11/2025: TBA, at 13:00 in U168.
Title: TBA
Abstract: TBA
2/12/2025: TBA, at 13:00 in U168.
Title: TBA
Abstract: TBA
9/12/2025: TBA, at 13:00 in U164.
Title: TBA
Abstract: TBA
16/12/2025: TBA, at 13:00 in U164.
Title: TBA
Abstract: TBA
Page updated
Google Sites
Report abuse