The Fields Medal winner Caucher Birkar (L) of Iran shakes hands with Shigefumi Mori (R), President of the International Mathematical Union (IMU) Executive Committee, during the opening ceremony of the 2018 International Congress of Mathematicians in Rio de Janeiro, Brazil, on Aug. 1, 2018. Mathematicians from Germany, India, Iran and Italy were awarded the prestigious Fields Medal during the International Congress of Mathematicians held in Rio de Janeiro on Wednesday. (Xinhua/Li Ming)