28Th Annual Acm Symposium on Applied Computing, Sac 2013, Date: 18 March 2013 through 22 March 2013, Location: Coimbra, Sponsors: ACM Special Interest Group on Applied Computing (SIGAPP);ISEC Engenharia;Politecnico de Coimbra;Caixa Geral de Depositos;Institute of Systems and Robotics (ISR), University of Coimbra