Title:  Hopf Lefschetz theorem for posets

Abstract:  The Hopf-Lefschetz theorem is a classical fixed point result from topology relating the Euler characteristic and the traces of certain matrices. In this talk we will prove a generalization of this theorem to order preserving maps on posets due to Baclawski and Björner. Additionally, we will prove a number of sufficient conditions on a poset P guaranteeing that all order preserving maps on P have a fixed point.