Book DescriptionThis book constitutes the thoroughly refereed post-proceedings of the 4th International Workshop on Multi-Agent-Based Simulation, MABS 2003, held in Melbourne, Australia as part of AAMAS 2003 The 11 revised full papers presented togetherwith 3 invited papers were carefully selected during two rounds of reviewing and improvement озмои The papers are organized in topical sections on MABS techniques for MAS; economics, exchange, and influence in virtual worlds; MABS techniques for real-world modelling, and understanding and classifying MABS. Economi2004 г 209 стр ISBN 3540207368.