## Acyclic orientations and excedence permutations

### Stephanie van Willigenburg, (UBC)

Abstract: The cardinality of a set of certain directed bipartite graphs is

equal to that of a set of permutations that satisfy certain criteria. In
this

talk we decribe both the set of graphs and the set of permutations, what

their cardinality has to do with the chromatic polynomial, and whether we
can

find a natural bijection between the sets.

This is joint work with Richard Ehrenborg.