Following Katz-Nishinou, we will compute the number of lines on
a quintic threefold in $\mathbb P^4$ by degenerating the quintic to
the union of coordinate hyperplanes. This motivates degeneration
formulae in Gromov-Witten theory that I will give...
Logarithmic Gromov-Witten invariants generalize usual and
relative Gromov-Witten invariants and were first suggested by
Siebert and then recently introduced by Gross-Siebert and
Abramovich-Chen. Applications include more general
degeneration...
