The IBS Discrete Mathematics Group welcomes Chong Shangguan and Yisai Xue, two long-term visitors to ECOPRO group.
![](https://dimag.ibs.re.kr/cms/wp-content/uploads/2023/05/chong-300x300.jpg)
Chong Shangguan (上官冲) is a professor at Shandong University and will stay with us for 3 months.
![](https://dimag.ibs.re.kr/cms/wp-content/uploads/2023/05/yisai-1-300x300.jpg)
Yisai Xue is a graduate student at Shanghai University and will stay with us for 1 year.