Summary: Self-reproduction in cellular automata is discussed with reference to the models of von Neumann and Codd. The conclusion is drawn that although the capacity for universal construction is a sufficient condition for self- reproduction, it is not a necessary condition. Slightly more ”liberal” criteria for what constitutes genuine self-reproduction are introduced, and a simple self-reproducing structure is exhibited which satisfies these new criteria. This structure achieves its simplicity by storing is description in a dynamic ”loop”, rather than on a static ”tape”.
[For the entire collection see Zbl 0556.00013.]