A recursive construction of a Celtic-key pattern.

A particular Celtic-key pattern, dating from around 1000 AD, displays conspicuous self-similarity. Such self-similar structures, although rare, are not unknown in the medieval period, but it is unlikely that there was a well-developed concept of recursion at that time. In the other cases it is possible to infer a plausible origin for self-similarity in pre-existing techniques of design and construction, but the inspiration for this example remains obscure. Nevertheless the recursive structure allows the use of modern methods to reproduce the pattern, and develop it further. [ABSTRACT FROM AUTHOR]