1. School of Computing and Mathematic Sciences, University of Leicester, Leicester LE1 7RH, UK
2. Department of Information Systems, Faculty of Computing and Information Technology, King Abdulaziz University, Jeddah 21589, Saudi Arabia
3. Department of Electrical Engineering and Computer Science, Howard University, Washington, DC 20059, USA
4. Institute of Applied Informatics, Department of Computer Science, University of South Bohemia, CZ-370 05 České Budějovice, Czech Republic