Affiliation: | 1 Dept. of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, UK. Email: pp{at}ecs.soton.ac.uk 2 Dept. of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, UK. Email: nrj{at}ecs.soton.ac.uk 3 Dept. of Computing Science, University of Aberdeen, Aberdeen AB24 3UE, UK. Email: tnorman{at}csd.abdn.ac.uk |