1. CIRRELT and Département d’informatique et de recherche opérationnelle, Université de Montréal, Montreal, Quebec H3T 1J4, Canada;
2. INESC TEC, Porto 4200-465, Portugal;
3. Erasmus Q-Intelligence, 3000 DR Rotterdam, Netherlands;
4. School of Engineering, Polytechnic of Porto, Porto 4249-015, Portugal;
5. CMAFCIO and Faculdade de Ciências da Universidade de Lisboa, Lisboa 1749-016, Portugal