Maybe AlphaGo is fallible after all. Korean Go master Lee Sedol claimed victory over Google DeepMind鈥檚 Go-bot on Sunday, his first in the five-game series.
It came too late to affect the outcome of the series 鈥� AlphaGo clinched it on Saturday with its third straight win. But Lee鈥檚 victory reversed the event鈥檚 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 鈥淟EE-SE-DOL鈥�. 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.
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鈥淚f I had lost one game, it would have hurt tremendously,鈥� he said. 鈥淏ut because I lost three matches and got this single win, I wouldn鈥檛 exchange it for anything in the world.鈥�
The day before, he had lost to AlphaGo鈥檚 most complete performance yet, falling behind early and never recovering.
鈥淚t was so hard to watch,鈥� said Andrew Jackson of the . 鈥淗e just got steamrolled.鈥�
Astonishing play
In Sunday鈥檚 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鈥檚 rivals, commenting on the game in China, called it the 鈥渉and of god鈥�, 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鈥檚 founders, AlphaGo didn鈥檛 realise its mistake until eight moves later. 鈥淟ee Sedol beat AlphaGo at its own game,鈥� said Jackson.
Watch the best human player take on the mighty AlphaGo AI at Go
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: 鈥淭he result 鈥榳hiteresign鈥� was added to the game information. AlphaGo resigns.鈥�
Lonely fight
After the third match, with camera shutters clicking, Lee had apologised 鈥渇or not being able to satisfy a lot of people鈥檚 expectations鈥�. More than one reporter later admitted to holding back tears. Lee stressed it was not humanity鈥檚 defeat, but his alone. He said that the pressure had got to him, and that he felt 鈥渒ind of powerless鈥�.
One of Lee鈥檚 fellow pros, Lee Hyun-wook, paid tribute to his heart and spirit. 鈥淗e is fighting such a lonely fight, and a hard fight against this invisible opponent.鈥�
The next day was an emotional 180. Yet, in his moment of victory, if Lee cracked a smile, I didn鈥檛 see it. His focus was back on the board, replaying the game.
In Go, it鈥檚 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鈥檚 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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