Institution: | A1 Department of Artificial Intelligence, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1081a, 1081 HV Amsterdam, The Netherlands. E-mail: marx@cs.vu.nl A2 Department of Computer Science, King's College London, Strand, London WC2R 2LS, UK. E-mail: {szabolcs, schlobac}@dcs.kcl.ac.uk |