1. Department of Applied Mathematics, College of Science, China Agricultural University, Beijing, People's Republic of China
2. LSEC, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing, People's Republic of China
3. GERAD and Department of Mathematics and Industrial Engineering, Polytechnique Montréal, Montreal, QC, Canada
4. Systems Optimization Laboratory, Department of Management Science and Engineering, Stanford University, Stanford, CA, USA