Game Over! AlphaGo defeats grandmaster

Google DeepMind's computer program AlphaGo on Saturday beat South Korean grandmaster Lee Sedol in game three of a historic five-game Go match. AlphaGo won by resignation after 176 moves, according to a statement by Google.

"AlphaGo created a large territory on the board, but Lee Sedol used a few innovative tactics to start a huge all-or-nothing ko fight and complicate the situation," the statement read. "In the resulting ko fight, AlphaGo prevailed."

The game Go, which originated in ancient China, is considered one of the most difficult games for a computer program to master due to the sheer amount of possibilities.

The mathematical permutations are complex. They depend on the size of a board and the length of a game. Typical Go games end with consent from the two players - not when all possible moves are exhausted. The total number of theoretically possible scenarios can exceed the number of observable atoms in the universe.

In October, the DeepMind-developed program beat three-time European Go champion and Chinese professional Fan Hui, marking the first time a computer claimed a victory against a human in the difficult game.

October's game was a milestone in the development of AI, with DeepMind CEO Demis Hassabis describing the feat as the biggest challenge since Russian world chess champion Garry Kasparov lost to IBM supercomputer Deep Blue in 1997.

Work of art

American professional Go player Michael Redmond, who served as the match's commentator, said Lee Sedol was not playing "his true style" in the first two games, but "his own game" stood out during Saturday's game.

"Today, Lee was definitely playing his own game, from his strong open to the complicated move in the final ko," said Redmond, who is also the only Westerner to achieve 9-dan, the game's highest grade.

"AlphaGo was ready for everything, including the ko fights, and was able to take the win. I'd like to congratulate the people who actually made this accomplishment possible, because it's a work of art," added Redmond.

'Incredible genius'

Meanwhile, DeepMind CEO Demis Hassabis congratulated Lee Sedol, extolling his "incredible genius."

"Historic moment. In complete awe of Lee Sedol's incredible genius, and proud of the amazing AlphaGo team," Hassabis wrote in a tweet.

Lee Sedol and AlphaGo will play the final two games in the match to determine the final match score.