In this chapter we investigate the automata counterpart of the sticker systems studied in the previous chapter. We consider a new type of automata, working on tapes which are double stranded sequences of symbols related by a complementarity relation, similar to a DNA molecule (such a data structure is called a Watson-Crick tape). The automata scan separately each of the two strands, in a correlated manner. They can also have a finite number of states controlling the moves and/or they can have an auxiliary memory which is also a Watson—Crick tape, used in a FIFO-like manner Combining such possibilities we obtain several types of automata. In most cases, these automata augmented with squeezing mechanisms, such as weak codings and deterministic sequential transducers, characterize the recursively enumerable languages.
KeywordsCoherence Prefix Suffix
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