The trace formula is an important tool in the theory of automorphic forms. It was invented by Selberg in the rank one case and vastly generalized by Arthur. In the higher rank case a ubiquitous role is played by volumes of certain polytopes and operator valued analogues thereof. A key point is a non-commutative analogue of a tessellation argument of P. McMullen and R. Schneider.
Applications to spectral asymptotics of locally symmetric spaces will also be discussed.
No prior knowledge of these subjects is assumed. Joint work with Tobias Finis and Werner Muller