Affiliation: | (1) School of Computer Science, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland;(2) Department of Electronics and Computer Engineering, University of Surrey, England;(3) IRIT, 118 route de Narbonne, 31062 Toulouse, France;(4) DIW, Königin-Luise-Str. 5, 14195 Berlin, Germany |