Counting curves via lattice paths in polygons

This Note presents a formula for the enumerative invariants of arbitrary genus in toric surfaces. The formula computes the number of curves of a given genus through a collection of generic points in the surface. The answer is given in terms of certain lattice paths in the relevant Newton polygon. If the toric surface is $\text{P}{}^2$ or $\text{P}{}^1\text{×}\text{P}{}^1$ then the invariants under consideration coincide with the Gromov–Witten invariants. The formula gives a new count even in these cases, where other computational techniques are available. To cite this article: G. Mikhalkin, C. R. Acad. Sci. Paris, Ser. I 336 (2003).