Alan Dix School of Computing and Mathematics The University of Huddersfield Queensgate, Huddersfield, HD1 3DH United Kingdom Tel: +44 1484 472 758 Fax: +44 1484 421 106 or Francesmary Modugno Computer Science and Engineering, FR 35 Box 352350 University of Washington Seattle, Washington 98195 USA Tel: +1 206 543 8099 Fax: +1 206 543-2969