  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, $\{X^i \}$ and their dual partners, $\{Y_i \}$, 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.
