  Ekedahl, Lando, Shapiro, and Vainshtein announced a remarkable formula
expressing Hurwitz numbers (counting covers of the projective line with
specified simple branch points, and specified branching over one other point)
in terms of Hodge integrals. We give a proof of this formula using virtual
localization on the moduli space of stable maps, and describe how the proof
could be simplified by the proper algebro-geometric definition of a "relative
space".
