Title:   The Waldschmidt constant of squarefree monomial ideals

In this talk, I will introduce the Waldschmidt constant of an ideal in a polynomial ring, and explain why one may be interested in this invariant. Although it is very hard to compute this value, I will show that in the case of squarefree monomial ideals, one can show that the Waldschmidt constant is a solution of a suitable linear program that is constructed from the primary decomposition of the ideal. This leads to a nice combinatorial interpretation of this value in terms of the fractional chromatic number of an associated hypergraph.