Seminar series
Date
Tue, 25 Nov 2025
15:00
15:00
Location
L6
Speaker
William Boulanger, Emma Harvey, Yizhi Li
Organisation
Oxford University
Definability of a property, in the context of operator algebras, can be thought of as invariance under ultraproducts. William Boulanger, Emma Harvey, and Yizhi Li will show that free independence of elements, a concept from Voiculescu's free probability theory, does not lift from ultrapowers, and is thus not definable, either over C*-probability spaces or tracial von Neumann algebras. This fits into the general interest of lifting n-independent operators.
This talk comes from a summer research project supervised by J. Pi and J. Curda.