Google's AlphaGo defeats Go grandmaster Lee Sedol in final match (6)

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)