Reducing the complexity of logics for multiagent systems Marcin Dziubiński Department of Economics, Lancaster University, LA1 4YX Lancaster, UK Rineke Verbrugge Institute of Artificial Intelligence, University of Groningen, Grote Kruisstraat 2/1, 9712 TS Groningen, The Netherlands NIAS Meijboomlaan 1, 2242 PR Wassenaar, The Netherlands Barbara DuninKęplicz Institute of Informatics, Warsaw University, Banacha 2 02097 Warsaw, Poland Institute of Computer Science Polish Academy of Sciences, Ordona 21 01237 Warsaw, Poland NIAS Meijboomlaan 1, 2242 PR Wassenaar, The Netherlands Theories of multiagent systems (MAS), in particular those based on modal logics, often suffer from a high computational complexity. This is due in part to the combination of agents' individual attitudes (beliefs, goals and intentions), and even more importantly to the presence of group attitudes, such as common belief and collective intention. pdflogo.jpg AAMAS07_0064_788edd873282674477c89e20c1ef8d30