Department of Computer Science and Operations Research, Université de Montréal, Québec, Canada. csuros@iro.umontreal.ca|Department of Computer Science and Operations Research, Université de Montréal, Québec, Canada. csuros@iro.umontreal.ca|Department of Computer Science and Operations Research, Université de Montréal, Québec, Canada. csuros@iro.umontreal.ca