SPEAKER: Jonathan Brundan

TITLE: Good grading polytopes.

ABSTRACT I'll define some polytopes associated to nilpotent orbits in a semisimple Lie algebra g. They live in the same space as the restrictions of some hyperplane arrangements associated to the root system of g, first studied by Orlik and Solomon. I'll try to explain why I cared but mainly focus on old results of Orlik, Solomon, Sommers and Douglass.