%0 Journal Article %T K-theoretic matching of brane charges in S- and U-duality %A Stefan Mendez-Diez %A Jonathan Rosenberg %J Mathematics %D 2010 %I arXiv %R 10.4310/ATMP.2012.v16.n6.a1 %X We discuss K-theoretic matching of D-brane charges in the string duality between type I on the 4-torus and type IIA on a K3 surface. This case is more complex than the familiar case of IIA/IIB duality, which is already well understood, but it turns out that replacing K3 by its orbifold blow-down seems largely to resolve the apparent problems with the theory. In particular, this allows for precise matching of 2-torsion brane charges. %U http://arxiv.org/abs/1007.1202v3