1. Faculty of Computer & Mathematical Sciences, Universiti Teknologi MARA, Johor Branch, Segamat Campus, Johor 85000, Malaysia
2. College of Global Talents, Beijing Institute of Technology, Zhuhai, China
3. Department of Mathematics, The Chinese University of Hong Kong, Shatin, Hong Kong
4. Department of Mathematics, San José State University, San José, CA 95192, U.S.A.