  In this paper, we derive decay rates of the solutions to the incompressible
Navier-Stokes equations and Hall-magnetohydrodynamic equations. We first
improve the decay rate of weak solutions of these equations by refining the
Fourier splitting method with initial data in the space of pseudo-measures. We
also deal with these equations with initial data in Lei-Lin spaces and find
decay rates of solutions in Lei-Lin spaces.
