Institution: | (1) School of Computer Science, Tel-Aviv University, P.O.B. 39040, Ramat-Aviv, IL-69978 Tel-Aviv, Israel;(2) Centre de Mathématiques et Informatique de Marseille, LIF-CMI, 39, rue Joliot-Curie, F-13453 Marseille Cedex 13, France;(3) Institute of Computer Science, Polish Academy of Sciences, Ordona 21, PL-01-237 Warsaw, Poland |