Joint with Dagan Karp
We compute the local Gromov-Witten invariants of the "closed vertex", that
is, a configuration of three rational curves meeting in a single triple
point in a Calabi-Yau threefold. The method is to express the local
invariants of the vertex in terms of ordinary Gromov-Witten invariants of a
certain blowup of CP^3 and then to compute those invariants via the
geometry of the Cremona transformation.