1. Guido Salimbeni, Department of Computing, Goldsmiths University of London, London, SE14 6NW, U.K. Email: g.salimbeni@gold.ac.uk.
2. Frederic Fol Leymarie, Department of Computing, Goldsmiths University of London, London, SE14 6NW, U.K. Email: ffl@gold.ac.uk.
3. William Latham, Department of Computing, Goldsmiths University of London, London, SE14 6NW, U.K. Email: w.latham@gold.ac.uk.