[1] Intelligent Computer Systems Centre,
[2] Faculty of Computer Studies & Mathematics,undefined
[3] University of the West of England,undefined
[4] Bristol,undefined
[5] BS16 1QY e-mail jim@btc.uwe.ac.uk,undefined
[6] Department of Computer Studies,undefined
[7] Napier University Craiglockhart Campus,undefined
[8] 219 Collinton Road,undefined
[9] Edinburgh EH14 1DG e-mail T.Fogarty@dcs.napier.ac.uk,undefined