Tuesday 21 April 2026, 16:00 - 17:00 in HG 00.310
Hessel Posthuma (UvA)
A higher Lefschetz theorem for proper actions of discrete groups
The Atiyah-Singer index theorem gives a topological formula for the index of Dirac operators on compact manifolds, building a bridge between analysis and topology. The fundamental idea behind higher index theory is that in the presence of symmetries, an even richer connection becomes visible. In this talk I’ll give an introduction to a higher index theorem of this type, given by a fixed-point formula for a proper action of a discrete group. This is based on joint work with Paolo Piazza, Yanli Song and Xiang Tang.