This is joint work with Dr. Vladimir Lifschitz, at the University of Texas, Austin. The goal of this research is to develop, study and implement formalisms for representing properties of actions in declarative extensions of logic programming. The theoretical part of the project is based on the mathematical theory of nonmonotonic reasoning. The experimental part uses deductive database systems. The specific aims are (1) to develop methods for representing properties of actions using both negation as failure and classical negation, and to study their relation to the representations based on circumscription and other nonmonotonic formalisms, (2) to implement these representations using deductive database systems, (3) to extend this work to the models of action that include continuous time and concurrency, (4) to investigate the possibility of using abductive logic programming for the automation of reasoning about the past.
