This volume contains 6 invited lectures and 13 submitted contributions to the scientific programme of the international workshop Fundamentals of Artificial Intelligence Research, FAIR '91, held at Smolenice Castle, Czechoslovakia, September 8-12, 1991, under the sponsorship of the European Coordinating Committee for Artificial Intelligence, ECCAI. FAIR'91, the first of an intended series of international workshops, addresses issues which belong to the theoretical foundations of artificial intelligence considered as a discipline focused on concise theoretical description of some aspects of...