This Symposium presents original papers on the relation of artificial intelligence to the mathematical theory of computation. These papers by distinguished authors cover the relevant aspects of this topic. They are mostly research papers and some are historical papers tracing the development of the field. A volume of proceedings of the Symposium is to be published by Academic Press. The Symposium is expected to make a contribution to the field of artificial intelligence by extending extant work on artificial intelligence theory and by bringing together diverse strands of it. This event is held at Stanford University on September 6 and 7, 1991. One of the leading pioneers of artificial intelligence is Professor John McCarthy. The Symposium recognizes his important contributions to the field and many of the presenters are his students and colleagues.