IR DYNAMICS ON BRANES AND SPACE-TIME GEOMETRY

the type I theory compactified on T-3. When the D5-brane wraps the T-3 it yields a D2-brane in seven dimensions. In the leading approximatio n the moduli space of vacua of the three dimensional field theory on t he brane is T-4/Z(2). The dual M theory description of this theory is a compactification on K3 and our 2-brane is the eleven dimensional 2-b rane at a point in K3. We use this fact to conclude that strong coupli ng IR effects in the three dimensional theory on the brane turn its mo duli space into a K3. This interpretation allows us to solve various s trongly coupled gauge theories in three dimensions by identifying thei r Coulomb branch with a piece of a (sometime singular) K3.