  Pattern formation exhibited by a two-dimensional reaction-diffusion system in
the fast inhibitor limit is considered from the point of view of interface
motion. A dissipative nonlocal equation of motion for the boundary between high
and low concentrations of the slow species is derived heuristically. Under
these dynamics, a compact domain of high concentration may develop into a
space-filling labyrinthine structure in which nearby fronts repel. Similar
patterns have been observed recently by Lee, McCormick, Ouyang, and Swinney in
a reacting chemical system.
