Yongmei Liu, Hector J. Levesque. A Tractability Result for Reasoning with Incomplete First-Order Knowledge Bases. In Georg Gottlob, Toby Walsh, editors, IJCAI-03, Proceedings of the Eighteenth International Joint Conference on Artificial Intelligence, Acapulco, Mexico, August 9-15, 2003. pages 83-88, Morgan Kaufmann, 2003.
Abstract is missing.