Comparison of algebraic and symplectic Gromov-Witten invariants
We will discuss the definition of GW-invariants in general terms,
the motivation behind the search for virtual moduli cycles, and the
analytic and algebraic definitions of virtual cycles. We will explain
the key to the equivalence to these two definitions. The GW-invariants
are an example in whose study the notion of virtual cycles is essential.
Winter 1998 meeting of the PNGS