Cycle classes of divisorial Maroni loci

Hurwitz spaces are the moduli spaces of covers of given genus
and degree of the projective line. There are natural divisors in these
moduli spaces that generalize the divisor that Maroni defined for
trigonal covers. The problem is to calculate the cycle classes in the
compactified Hurwitz spaces. We define effective cycles that extend
the Maroni divisors and calculate their classes. This is joint work
with Alexis Kouvidakis.