Paul Johnson
<br>
Title: Hurwitz numbers and moduli spaces of curves"
<br>
Abstract: 
Hurwitz numbers count covers of curves with specified
ramification.  Hurwitz
numbers can also be interpreted in terms of group theory or
graphs on
surfaces, and these disparate viewpoints mean Hurwitz theory
arises in many
different contexts.

We'll give something of a survey of Hurwitz numbers, with a
focus on
``ELSV-type formulas", which express intersection numbers on
moduli spaces
of curves with some extra structure in terms of Hurwitz numbers.