[1] Hewlett Packard Labs, Bristol, Avon, England
[2] Queensland Univ Technol, Brisbane, Qld, Australia
[3] Shanghai Jiao Tong Univ, Shanghai, Peoples R China
[4] Univ Tsukuba, Tsukuba, Ibaraki 305, Japan
[5] JAIST, Tokyo, Japan
[6] Univ Wollongong, Wollongong, NSW 2500, Australia
[7] Ecole Normale Super, F-75231 Paris, France
[8] Katholieke Univ Leuven, Louvain, Belgium
[9] Univ Bristol, Bristol BS8 1TH, Avon, England
[10] Univ Wollongong, Wollongong, NSW 2500, Australia
[11] Nanyang Technol Univ, Singapore, Singapore
[12] City Univ Hong Kong, Hong Kong, Hong Kong, Peoples R China