1. Intelligence and Interaction Research Center, Korea Institute of Science and Technology, P.O.BOX 131, Cheongryang, Seoul, Korea. emmous@kist.re.kr
2. School of Computing, Queen's University, Kingston, Ontario K7L 3N6, Canada. ksalomaa@cs.queensu.ca
3. Department of Computer Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR. dwood@cs.ust.hk