Olof Bergvall: Topology and combinatorics of arrangements

An arrangement is a finite set of subvarieties of a variety. Despite their simple definition, arrangements are of interest to a wide range of areas of mathematics such as algebraic geometry, topology, combinatorics, Lie theory and singularity theory.

Classically, most attention has been given to arrangements of hyperplanes in an affine space but this is by no means the only case of interest. This talk will give an introduction to the subject of arrangements and say something about what happens beyond the hyperplanes. In particular, we will see how to compute the Poincaré polynomial of (the complement of) an arrangement of hypertori.