1. School of Science and Technology, Nottingham Trent University, Nottingham, UK. E-mail: jon.robinson@ntu.ac.uk
2. School of Information Technology, Deakin University, Melbourne, Australia. E-mail: kevin.lee@deakin.edu.au
3. Department of Computer Science, University of York, York, UK. E-mail: kofi.appiah@york.ac.uk