  Diffusion-limited reaction A+A->inert with anisotropic hopping on the d=1
lattice, is solved exactly for a simultaneous updating, discrete time-step
dynamics. Diffusion-dominated processes slow down as the anisotropy increases.
For large times or large anisotropy, one can invoke the appropriate continuum
limits. In these limits the effects of the anisotropy on variation of particle
density can be absorbed in time rescaling. However, in other regimes, when the
discreteness of the time steps is nonnegligible, the anisotropy effects are
nontrivial, although they are always quite small numerically.
