This book constitutes the refereed proceedings of the 21st International Conference on Principles and Practice of Multi-Agent Systems, PRIMA 2018, held in Tokyo, Japan, in October/November 2018. The 27 full papers presented and 31 short papers were carefully reviewed and selected from 103 submissions. PRIMA presents subjects in many application domains, particularly in e-commerce, and also in planning, logistics, manufacturing, robotics, decision support, transportation, entertainment, emergency relief and disaster management, and data mining and analytics.

This book constitutes the refereed proceedings of the second International Workshop on the Theory and Applications of Formal Argumentation, TAFA 2013, held in Beijing, China, in August 2013. The Workshop was co-located with IJCAI 2013. The 15 revised full papers presented were carefully reviewed and selected from 22 submissions. The papers are organized in topical sections such as abstract argumentation frameworks, social abstract argumentation with votes on attacks, a normal form of argumentation frameworks, assumption-based argumentation, argument schemes for normative practical reasoning.

This book constitutes the thoroughly refereed proceedings of the First International Workshop on the Theory and Applications of Formal Argumentation, TAFA 2011, held in Barcelona, Spain, in Juli 2011, as a workshop at IJCAI 2011, the 22nd International Joint Conference on Artificial Intelligence. The 9 revised full papers presented together with 8 revised poster papers were carefully selected during two rounds of reviewing and improvement from 32 initial submissions. The workshop promotes and fosters uptake of argumentation as a viable AI paradigm with wide ranging application, and provides a forum for further development of ideas and the initiation of new and innovative collaborations. The papers cover the following topics: properties of formal models of argumentation; instantiations of abstract argumentation frameworks; relationships among different argumentation frameworks; practical applications of formal models of argumentation; argumentation and other artificial intelligence techniques; evaluation of formal models of argumentation; validation and evaluation of applications of argumentation.

This book constitutes the refereed proceedings of the 4th International Workshop on the Theory and Applications of Formal Argumentation, TAFA 2017, held in Melbourne, VIC, Australia, in August 2017. The workshop was co-located with International Joint Conference on Artifi cial Intelligence(IJCAI 2017). The 15 revised full papers presented were carefully reviewed and selected from 20 submissions. The workshops covers the subjects such as non-monotonic reasoning, decision making, inter-agent communication, the semantic web, grid applications, ontologies, recommender systems, machine learning, neural networks, trust computing, normative systems, social choice theory, judgement aggregation and game theory, and law and medicine.

This book constitutes the refereed proceedings of the Third International Workshop on the Theory and Applications of Formal Argumentation, TAFA 2015, held in Buenos Aires, Argentina, in July 2015. The workshop was co-located with IJCAI 2015. The 15 revised full papers presented were carefully reviewed and selected from 25 submissions. The papers deal with formal theoretical models of argumentation and application of such models in subfields of AI, evaluation of models, both theoretical and practical, and theories and applications developed through inter-disciplinary collaboration.

This book constitutes the thoroughly refereed post-conference proceedings of the 10th International Workshops on Coordination, Organizations, Institutions and Norms in Agent Systems, COIN 2014. The workshops were co-located with AAMAS 2014, held in Paris, France, in May 2014, and with PRICAI 2014, held in Gold Coast, QLD, Australia, in December 2014. The 16 full papers were carefully reviewed and selected for inclusion in this volume. The papers cover a wide range of topics from work on formal aspects of normative and team based systems, to software engineering with organisational concepts, to applications of COIN based systems, and to philosophical issues surrounding socio-technical systems. They highlight not only the richness of existing work in the field, but also point out the challenges and exciting research that remains to be done in the area.