Non-perturbative results on the point particle limit of N=2 heterotic string compactifications

Using heterotic/type II string duality, we obtain exact non-perturbative results for the point particle limit (alpha' --> 0) of some particular four dimensional, N = 2 supersymmetric compactifications of heterotic strings. This allows us to recover recent exact non-perturbative results on N = 2 gauge theory directly from tree-level type II string theory, which provides a highly non-trivial, quantitative check on the proposed string duality. We also investigate to what extent the relevant singular limits of Calabi-Yau manifolds are related to the Riemann surfaces that underlie rigid N = 2 gauge theory.