With this edition, EPIA, the Portuguese Conference on Arti?cial Intelligence, celebrates its 20th anniversary.Like all its previous editions, it has been run - der the auspices of the Portuguese Association for Arti?cial Intelligence (APPIA), which was established in 1984 and is also celebrating 20 years of activity. The ?rst edition of EPIA was held in Porto, in October 1985, organised by Pavel Brazdil, Miguel Filgueiras, Lu 's Damas and Armando Campos e Matos. EPIA soon evolved to an international conference by adopting in its fourth edition English as the o?cial language and having its proceedings published by Springer, intheLNAIseries.Inrecentyears, theconferencegraduallyprogressed from a plenary organisation to a workshop-based structure. The conference has steadily assumed high-quality standards, both in its scienti?c management and in the scienti?c program, with the aim of progressively broadening its audience and improving its impact over young researchers. EPIA2005wasthe12theditionoftheconference.With theabove-mentioned celebrations in mind, we decided to work towards the involvement of several generations of AI researchersin the organisationof the event. As a result, EPIA 2005 involved for the ?rst time an Advisory Committee, composed of all the founders of APPIA that are still working in AI, and also the Co-chairs of the lastEPIAs, as listed elsewherein these proceedings.We wantto express to them our gratitude for all the support, advice and con?dence.

This book constitutes the proceedings of the 5th International Conference on Social Informatics, SocInfo 2013, held in Kyoto, Japan, in November 2013. The 23 full papers, 15 short papers and three poster papers included in this volume were carefully reviewed and selected from 103 submissions. The papers present original research work on studying the interplay between socially-centric platforms and social phenomena.