South Korean Go master Lee Se-dol has won his first match against Google’s AlphaGo program, after losing three in a row in a best-of-five competition in Seoul.
Lee Se-dol, one of the world’s top Go players, said his win against AlphaGo was “invaluable”.
Go is considered to be a much more complex challenge for a computer than chess, and AlphaGo’s wins were seen as a landmark moment for artificial intelligence.
A fifth game will be played on March 15.
Go is a game of two players who take turns putting black or white stones on a 19-by-19 grid. Players win by surrounding their opponents’ pieces with their own.
Commentator Michael Redmond said AlphaGo had been playing well up until the middle of the game, but at move 78, Lee Se-dol played brilliantly.
Speaking after his victory, Lee Se-dol said: “I’ve never been congratulated so much because I’ve won one game.”
Google representatives said the defeat was “very valuable” for AlphaGo, as it identified a problem which they could now try to fix.
In the first game of the series, AlphaGo triumphed by a very narrow margin – Lee Se-dol had led for most of the match, but AlphaGo managed to build up a strong lead in its closing stages.
After losing the second match to Deep Mind, Lee Se-dol said he was “speechless” adding that the AlphaGo machine played a “nearly perfect game”.
In the third game commentators said that Lee Se-dol had brought his “top game” but that AlphaGo had won “in great style”.
The AlphaGo system was developed by British computer company DeepMind which was bought by Google in 2014.