After Falling 3-0 Against Google's Go-Playing Computer Algorithm AlphaGo, Lee Sedol Battles Back

Lee Sedol, world champion of the Chinese abstract strategy board game Go, may have lost his best-of-five tournament against Google's AlphaGo computer algorithm and the $1 million prize that came with it, but he has eliminated the possibility of a sweep.

"Because I lost three matches and then was able to get one single win, this win is so valuable that I wouldn't exchange it for anything in the world," Lee told Wired after the AlphaGo artificial intelligence program resigned five hours into the match.

"That's because of the cheers and the encouragement that you all have shown me."

The press pool erupted into applause.

After losing his third straight game (and thereby the match) on Saturday at the Four Seasons hotel in Seoul, Lee was despondent.

"I don't know how to start or what to say today, but I think I would have to express my apologies first," he said, according to the news website Venturebeat.

"I should have shown a better result, a better outcome and better content in terms of the game played. And I do apologize for not being able to satisfy a lot of people's expectations. I kind of felt powerless. If I look back on the three matches, the first one, even if I were to go back and redo the first match, I think that I would not have been able to win, because I at that time misjudged the capabilities of AlphaGo."

Yet, Lee stopped short of calling the machine infallible.

"Although AlphaGo is a strong program, I would not say that it is a perfect program," he said. "Yes, compared to human beings, its moves are different and at times superior. But I do think there are weaknesses for AlphaGo."

And for the South Korean Go champion, ranked second in international titles behind Lee Chang Ho, exploiting those weaknesses came down to one move. According to Michael Redmond who's been calling the match for English viewers, that would be the 78th move, to be exact.

"Lee Sedol played a brilliant move," he said. "It took me by surprise. I'm sure that it would take most opponents by surprise. I think it took AlphaGo by surprise."

The fifth and final game between Lee and AlphaGo will be held on Tuesday.