1. Optimized Markets Inc., Pittsburgh, Pennsylvania 15213;
2. School of Industrial & Systems Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332;
3. CIRRELT & School of Management for École des Sciences de la Gestion, Université du Québec à Montréal, Montréal, Québec H3C 3P8, Canada;
4. CIRRELT & Department of Mathematics and Industrial Engineering, École Polytechnique de Montréal, Montréal, Québec H3C 3A7, Canada