1. Yau Mathematical Sciences Center, Tsinghua University, Beijing, People's Republic of China
2. School of Mathematics, Renmin University of China, Beijing, People's Republic of China
3. Key Laboratory of Mathematics, Informatics and Behavioral Semantics (LMIB) and School of Mathematical Sciences, Beihang University (Shahe campus), Beijing, People's Republic of China
4. Beijing Advanced Innovation Center for Imaging Theory and Technology, Academy for Multidisciplinary Studies, Capital Normal University, Beijing, People's Republic of China
5. Department of Mathematical Sciences, Tsinghua University, Beijing, People's Republic of China
6. Yanqi Lake Beijing Institute of Mathematical Sciences and Applications (BIMSA), Huairou, Beijing, People's Republic of ChinaDedicate to Professor Peter Caines on the occasion of his 75th birthday