D-INSTANTONS AND ASYMPTOTIC GEOMETRIES

The large-N limit of D-3-branes is expected to correspond to a superco nformal field theory living on the boundary of the anti-de Sitter spac e appearing in the near-horizon geometry. Dualizing the D-3-brane to a D-instanton, we show that this limit is equivalent to a type IIB S-du ality. In both cases one effectively reaches the near-horizon geometry . This provides an alternative approach to an earlier derivation of th e same result that makes use of the properties of a gravitational wave instead of the D-instanton.