This volume contains 6 invited lectures and 13 submittedcontributions to the scientific programme of theinternational workshop Fundamentals of ArtificialIntelligence Research, FAIR '91, held at Smolenice Castle,Czechoslovakia, September 8-12, 1991, under the sponsorshipof the European Coordinating Committee for ArtificialIntelligence, ECCAI. FAIR'91, the first of an intendedseries of international workshops, addresses issues whichbelong to the theoretical foundations of artificialintelligence considered as a discipline focused on concisetheoretical description of some aspects of intelligence bytoolsand methods adopted from mathematics, logic, andtheoretical computer science. The intended goal of the FAIRworkshops is to provide a forum for the exchange of ideasand results in a domain where theoretical models play anessential role. It is felt that such theoretical studies,their development and their relations to AI experiments andapplications have to be promoted in the AI researchcommunity.