  This paper establishes the L^p boundedness of wave operators for linear
Schrodinger equations in R3 with time-dependent potentials. The approach to the
proof is based on new cancellation lemmas. As a typical application based on
this method combined with Strichartz estimates, is the existence and scattering
for nonlinear dispersive equations. For example, we prove global existence for
a class of Hartree nonlinear Schroedinger equations in L^2(R^3); allowing the
presence of solitons.
