Self-reproduction in Reversible Cellular Automata
J. von Neumann first showed that machine self-reproduction is possible using the framework of cellular automaton (CA). In his CA, self-reproducing objects have universality in both computing and construction, and thus they were very complex. Later, Langton relaxed this condition, and designed a simple selfreproducing automaton. In this chapter, we study how self-reproducing automata are constructed in a reversible environment. It is shown that there are two- and threedimensional reversible cellular automata (RCAs), in which various objects called Worms and Loops can self-reproduce. Hence, Langton’s type self-reproduction is possible in RCAs. There, conversion between a shape of an object and its description (or gene), and copying the description are done reversibly. Using these properties, self-reproducing automata are designed in RCAs. An additional advantage of them is that the “shape-encoding mechanism” is employed, i.e., the shape of a Worm or a Loop is encoded into its description in a reversible way. This makes the whole mechanism simple, and increases the variety of self-reproducing objects.
Keywordsreversible cellular automaton three-dimensional cellular automaton self-reproduction shape-encoding mechanism
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