Chemical Processor for Computation of Skeleton of Planar Shape

In this paper we give a regular proof of the viability of the theory of reaction–diffusion computing. The test problem is to approximate the skeleton of a planar contour, i.e. select sites of centres of bitangent circles which lie wholly within the contour. We have designed both a cellular automaton model and a real prototype of a chemical processor that implement skeleton transformations. In the cellular automaton, segments of the discrete skeleton are computed via interactions of excitation waves, while in the chemical processor the underlying mechanism is the formation of Prussian blue in an agar gel film. © 1997 John Wiley & Sons, Ltd.