The mathematical theory of computation has given rise to two important ap­ proaches to the informal notion of "complexity": Kolmogorov complexity, usu­ ally a complexity measure for a single object such as a string, a sequence etc., measures the amount of information necessary to describe the object. Compu­ tational complexity, usually a complexity measure for a set of objects, measures the compuational resources necessary to recognize or produce elements of the set. The relation between these two complexity measures has been considered for more than two decades, and may interesting and deep observations have been obtained. In March 1990, the Symposium on Theory and Application of