Chen, Q., Torroni, P., Villata, S., Hsu, J., Omicini, A. (Eds.): PRIMA 2015: Principles and Practice of Multi-Agent Systems, 18th International Conference, Bertinoro, Italy, October 26-30, 2015, Proceedings. Lecture Notes in Artificial Intelligence 9387. Springer 2015, ISBN 978-3-319-25523-1. [order volume] [online version]