Computational Intelligence, Volume 12. Number 3. 1996 EFFICIENT TEMPORAL REASONING IN THE CACHED EVENT CALCULUS

This article deals with the problem of providing Kowalski and Sergot’s event calculus. extended with context dependency, with an efficient implementation in a logic programming framework. Despite a widespread recognition that a positive solution to efficiency issues is necessary to guarantee the computational feasibility of existing approaches to temporal reasoning, the problem of analyzing the complexity of temporal reasoning programs has been largely overlooked. This article provides a mathematical analysis of the efficiency of query and update processing in the event calculus and defines a cached version of the calculus that (i) moves computational complexity from query to update processing and (ii) features an absolute improvement of performance. because query processing in the event calculus costs much more than update processing in the proposed cached version. Key words: event calculus, temporal reasoning complexity, database query and update, caching. 1