Li Si (C), a professor at Yau Mathematical Sciences Center of Tsinghua University, receives Morningside Gold Medal of Mathematics award at the opening ceremony of the 7th International Congress of Chinese Mathematicians (ICCM) in Beijing, capital of China, Aug. 6, 2016. The congress is a triennial event that brings together Chinese and overseas mathematicians for the discussion of the developments of mathematics. (Xinhua/Cai Yang)