NONCRITICAL STRINGS, DEL-PEZZO SINGULARITIES AND SEIBERG-WITTEN CURVES

We study limits of four-dimensional type II Calabi-Yau compactificatio ns with vanishing 4-cycle singularities, which are dual to T-2 compact ifications of the six-dimensional non-critical string with E-8 symmetr y, We define proper sub-sectors of the full string theory, which can b e consistently decoupled. In this way we obtain rigid effective theori es that have an intrinsically stringy BPS spectrum, Geometrically the moduli spaces correspond to special geometry of certain non-compact Ca labi-Yau spaces of an intriguing form, An equivalent description can b e given in terms of Seiberg-Witten curves, given by the elliptic simpl e singularities together with a peculiar choice of meromorphic differe ntials. We speculate that the moduli spaces describe non-perturbative non-critical string theories, (C) 1997 Elsevier Science B.V.