Affiliation: | (1) Dept. of Computer Science, University of Toronto, 10 Kings College Rd., Toronto, ON, Canada, M5S 3G4;(2) National Research Council, Bldg. M-50, Rm 257, Montreal Rd., Ottawa, ON, Canada, K1A 0R6;(3) Dept. of Computer Science, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, Canada, V8W 3P6 |