In this expository article, we explain how to use localization to compute
Gromov-Witten invariants of smooth toric varieties and orbifold Gromov-Witten
invariants of smooth toric Deligne-Mumford stacks.
The ELSV formula, first proved by Ekedahl, Lando, Shapiro, and Vainshtein,
relates Hurwitz numbers to Hodge integrals. Graber and Vakil gave another proof
of the ELSV formula by virtual localization on moduli spaces of stable maps to
the projective line, and also explained how to simplify their proof using
moduli spaces of relative stable maps to the projective line relative to a
point. In this expository article, we explain what the ELSV formula is and how
to prove it by virtual localization on moduli spaces of relative stable maps,
following Graber-Vakil.
This is a follow-up paper to \cite{FLTZ}. We extend the
coherent-constructible correspondence of \cite{FLTZ} to include toric
orbifolds. A toric orbifold $\cX_\bSi$ is described by a "stacky fan" $\bSi$
lying in a real vector space $N_\bR,$ following Borisov-Chen-Smith \cite{BCS}.
In arXiv:math/0605587, the first two authors have constructed a
gauge-equivariant Morse stratification on the space of connections on a
principal U(n)-bundle over a connected, closed, nonorientable surface. This
space can be identified with the real locus of the space of connections on the
pullback of this bundle over the orientable double cover of this nonorientable
surface. In this context, the normal bundles to the Morse strata are real
vector bundles.
In arXiv:math/0605587, the first two authors have constructed a
gauge-equivariant Morse stratification on the space of connections on a
principal U(n)-bundle over a connected, closed, nonorientable surface. This
space can be identified with the real locus of the space of connections on the
pullback of this bundle over the orientable double cover of this nonorientable
surface. In this context, the normal bundles to the Morse strata are real
vector bundles.