(12) Anytime hypothetical reasoning

This project seeks to implement a hypothetical reasoning system which supports anytime query processing. A hypothetical reasoning system is one in which knowledge is represented as a triple consisting of a set of facts, a set of hypothesis which are tentative assertions and a set of constraints. A knowledge base in a hypothetical reasoning system can support multiple possible views of the world, called extensions.
An extension is one consistent way of extending the set of facts by adding tentative assertions from the set of hypotheses. The set of constraints specify those assertions that may not appear in an extension. Hypothetical reasoning systems typically support three kinds of queries: explanation, where the system attempts to identify minimal extensions which contain some observation as a logical consequence, set-membership, where the system attempts to determine if a given assertion is contained in some extension, and set-entailment, where the system attempts to determine if a given assertion is contained in all extensions.
Anytime algorithms, by definition, are preemptively schedulable, can be terminated at any time to obtain useful partial solutions and provide a guarantee of improved solution quality if they are allowed longer periods for processing.

Research Period :	June 1997 - February 1998
Cooperate Researchers :	R. G. Goebel Dept. of Computing Science, University of Alberta, Prof. Joseph Davis Decision Systems Lab, Dept. of Business Systems, University of Wollongong, Dr.