Yannis Dimopoulos, Bernhard Nebel, Francesca Toni. Preferred Arguments are Harder to Compute than Stable Extension. In Thomas Dean, editor, Proceedings of the Sixteenth International Joint Conference on Artificial Intelligence, IJCAI 99, Stockholm, Sweden, July 31 - August 6, 1999. 2 Volumes, 1450 pages. pages 36-43, Morgan Kaufmann, 1999.
Abstract is missing.