South Korean professional Go player Lee Sedol (R) presents the Go game board with his signature to Demis Hassabis, the CEO of Google's London-based AI company DeepMind during a press conference after finishing the final match of the Google DeepMind Challenge Match against Google's artificial intelligence program, AlphaGo, in Seoul, South Korea, March 15, 2016. Google's Go-playing computer program again defeated its human opponent in a final match on Tuesday that sealed its 4-1 victory. (Xinhua/Gang Ye)