AlphaGo’s victory in the ancient Chinese board game is a breakthrough for artificial intelligence, showing the program developed by Google DeepMind has mastered one of the most creative and complex games ever devised.
Commentators said the match was close, with both AlphaGo and Mr Lee making mistakes. The result was unpredictable until near the end.
Mr Lee’s loss was a shock to South Koreans and Go fans. The 33-year-old had been confident of victory two weeks ago, but sounded less optimistic a day before the match.
“I was very surprised because I did not think that I would lose the game. A mistake I made at the very beginning lasted until the very last,” said Mr Lee, who has won 18 world championships since the age of 12.
Mr Lee said AlphaGo’s strategy was “excellent”.
Yoo Chang-hyuk, another South Korean go master who commentated on the game, described the result as a big shock said that Mr Lee appeared to have been shaken at one point.
Hundreds of thousands of people watched the game live on television and YouTube. The remaining four matches will end on Tuesday.
Computers conquered chess in 1997 in a match between IBM’s Deep Blue and chess master Garry Kasparov, leaving go as “the only game left above chess” Demis Hassabis, Google DeepMind’s chief executive, said before the game.
Leading human players rely heavily on intuition ato choose among a near-infinite number of board positions in go, making the game extremely challenging for the artificial intelligence community.
AI experts had forecast it would take another decade for computers to beat professional go players.
That changed when AlphaGo defeated a European go champion last year, in a closed-door match later published in the journal Nature. Since then, AlphaGo’s performance has steadily improved.