Models of human inference

I would like to acknowledge the help of Gul Agha, Jonathon Amsterdam, Peter de Jong, Carl Manning, Richard Waldinger, and Fanya Montalvo in improving the presentation. I owe a tremendous intellectual debt to my colleagues in the Message Passing Semantics Group, the Tremont Research Institute, and the MIT Artificial Intelligence Laboratory. Ken Kahn, Ueda, Keith Clark, and Takeuchi helped me greatly to understand (Flat) Concurrent Prolog, (Flat) Parlog, and (Flat) Guarded Horn Clauses. This paper describes research done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Major support for the research reported in this paper was provided by the System Development Foundation. Major support for other related work in the Artificial Intelligence Laboratory is provided, in part, by the Advanced Research Projects Agency of the Department of Defense under Office of Naval Research contract N0014-80-C-0505. I would like to thank Carl York, Charles Smith, and Patrick Winston for their support and encouragement.