Sticker Systems

Abstract

Data structures basic in language theory are words,that is, strings of elements, letters. Here the idea of a “string” entails a linear order among the elements. The double helix of DNA, when presented in two dimensions as we have already done, constitutes a data structure of a new kind: a double strand. While both strands still are linear strings of elements, the double strand possesses an important additional property. The paired elements in the strands are complementary with respect to a given symmetric relation. We have already discussed the interconnection between this Watson—Crick complementarity and the twin-shuffle language The computational capacity of the latter has also been pointed out. In the next two chapters intensive use will be made of these two facts, the interconnection and computational capacity, for DNA computing. Our previous characterizations of recursively enumerable languages, based on equality sets and twin-shuffle languages, find here very natural applications.