1. School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China
2. Center for Optimization Technique and Quantitative Finance, Xi'an International Academy for Mathematics and Mathematical Technology, Xi'an, 710049, People's Republic of China
3. Department of Mathematics, Khalifa University of Science and Technology, P.O.Box 127788, Abu Dhabi, UAE
4. Department of Economics, University of Bergamo, Via dei Caniana 2, 24127 Bergamo, Italy