Another possible programming strategy is an idea that is actually due to Turing, who suggested that reaction-diffusion equations could be used to establish regular patterns. The slides shown above represent the spatial distribution of a reactant in a diffusion process. By changing a single parameter of the governing equation, the same system can lead to the very regular spots shown on the right, or the striped clustering shown on the left.
A programming mechanism based on reaction diffusion would be simple to set up using local communication, and seems ideally suited for use with surveillance dust when there is a need to logically group nearby elements together to form spatially organized groups to engage in a cooperative task.
Indeed, some people have proposed that these sorts of mechanisms are the way that the various cells in a Zebra coordinate their behavior to produce stripes.