A logic interpreter to handle time and negation in logic data bases

There is as yet no general agreement as to the best solution to the operation of time and negation in data bases. This paper presents an approach to handle these problems in a logic data base system. A simple logic interpreter is introduced that allows for effective reasoning based on the manipulation of a sequence of snapshots. These ideas have been realized in an extension to the query language Query-By-Example, which has been implemented in the logic programming language Prolog.