Noncommutative open string, D-brane and duality

We consider open strings ending on D-branes in the presence of constant metric, G, antisymmetric tensor, B and gauge field, A. The Hamiltonian is manifestly invariant under a global noncompact group; strikingly similar to toroidally compactified closed string Hamiltonian. The evolution equations for the string coordinates, {Xi} and their dual partners, {Yi}, are combined to obtain equations of motion invariant under the noncompact symmetry transformations. We show that one can start from a noncommutative theory, with nonvanishing G and B and mixed boundary conditions and then go over to a dual theory whose coordinates obey Dirichlet boundary conditions. It is possible to generate B-field by implementing the noncompact symmetry transformation. The connection between this duality transformation and Seiberg-Witten map is discussed.