Affiliation: | 1 Lab. Spécification et Vérification, CNRS, UMR 8643, ENS de Cachan, 61, av. du Pdt Wilson, 94235 Cachan Cedex, France. E-mail: demri{at}lsv.ens-cachan.fr 2 Automated Reasoning Group and Department of Computer Science, Australian National University, Canberra ACT 0200, Australia. E-mail: rpg{at}arp.anu.edu.au |