David Poole, Randy Goebel. Gracefully adding negation and disjunction to Prolog. In Ehud Y. Shapiro, editor, Third International Conference on Logic Programming, Imperial College of Science and Technology, London, United Kingdom, July 14-18, 1986, Proceedings. Volume 225 of Lecture Notes in Computer Science, pages 635-641, Springer, 1986.
Abstract is missing.