Maybe AlphaGo is fallible after all. Korean Go master Lee Sedol claimed victory over Google DeepMind’s Go-bot on Sunday, his first in the five-game series.
It came too late to affect the outcome of the series – AlphaGo clinched it on Saturday with its third straight win. But Lee’s victory reversed the event’s sombre tone, inspiring the Go community, and the entire region.
After his win, Lee strolled into a press conference to unrestrained cheers from reporters, chants of “LEE-SE-DOL”. He acknowledged them almost shyly, with a slight bow, his eyes on the floor. But the grin on his face was a picture of relief.
“If I had lost one game, it would have hurt tremendously,” he said. “But because I lost three matches and got this single win, I wouldn’t exchange it for anything in the world.”
The day before, he had lost to AlphaGo’s most complete performance yet, falling behind early and never recovering.
“It was so hard to watch,” said Andrew Jackson of the. “He just got steamrolled.”
In Sunday’s game, Lee started conservatively, ceding the centre of the board. But on move 78, he turned the game around with an astonishing wedge play in the middle. Gu Li, one of Lee’s rivals, commenting on the game in China, called it the “hand of god”, the kind of language that was being applied to AlphaGo in previous games.
AlphaGo responded to the unexpected move with a weak counter, which set off a brilliant sequence from Lee to capitalise. According to Demis Hassabis, one of DeepMind’s founders, AlphaGo didn’t realise its mistake until eight moves later. “Lee Sedol beat AlphaGo at its own game,” said Jackson.
Lee sat up straighter as he closed in on victory. The press room began to buzz as AlphaGo played increasingly bizarre moves, the death throes of an algorithm. Across the table from Lee, Aja Huang, the AlphaGo programmer who acts as its human avatar and places its stones on the board, appeared resigned. And then, a message appeared on his monitor: “The result ‘whiteresign’ was added to the game information. AlphaGo resigns.”
After the third match, with camera shutters clicking, Lee had apologised “for not being able to satisfy a lot of people’s expectations”. More than one reporter later admitted to holding back tears. Lee stressed it was not humanity’s defeat, but his alone. He said that the pressure had got to him, and that he felt “kind of powerless”.
One of Lee’s fellow pros, Lee Hyun-wook, paid tribute to his heart and spirit. “He is fighting such a lonely fight, and a hard fight against this invisible opponent.”
The next day was an emotional 180. Yet, in his moment of victory, if Lee cracked a smile, I didn’t see it. His focus was back on the board, replaying the game.
In Go, it’s customary to go over the match with your opponent to share your thought process. But across from Lee, there was only Aja Huang, looking around, unable to explain any of AlphaGo’s blunders. As he left his chair, Lee gave him barely a nod. In victory, just as in defeat, Lee Sedol was utterly alone.
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