1. Department of Computer Science, City University of Hong Kong, Kowloon Tong, Hong Kong
2. School of Computer Science, Chongqing University, Chongqing, China
3. Institute for Infocomm Research, Agency for Science, Technology and Research, Fusionopolis, Singapore
4. Department of Computing and Decision Sciences, Computational Intelligence Program, Lingnan University, Tuen Mun, Hong Kong