"In the second match Sedol displayed his newfound respect for AlphaGo by playing careful, flawless Go. It wasn’t designed to wow the 280 million people who would eventually watch the series, but from someone of Sedol’s rank, it constituted nearly unbeatable play, and Sedol exuded a quiet but unmistakable confidence. Then, as the game began to enter its middle phase, AlphaGo did something unusual: it instructed its human attendant to place a black stone in a largely unoccupied area to the right of the board. This might have made sense in another context, but on that board at that moment AlphaGo seemed to be abandoning the developing play in the lower half of the board. This historic move was something that no human would have feasibly played - AlphaGo calculated the probability that a human would play that move at 1 in 10,000. It produced instant shock and confusion among the spectators. Lee Sedol paled, excused himself, and left the room for a full fifteen minutes before returning.
The English-language commentators went silent before one said, with great understatement: “That’s a very surprising move.” At first Fan Hui, who was watching the game with Cade Metz, a writer for Wired magazine, was as befuddled as anyone else. “It’s not a human move,” he told Metz. “I’ve never seen a human play this move.” As Metz would later note, nothing in the 2,500 years of collected Go knowledge and understanding prepared anyone for move 37 of the second game in the series. Except Hui. Since losing to AlphaGo the previous fall Hui had spent hours helping the Google DeepMind team train the software for the match with Sedol, an experience that allowed him to understand how the move connected the black stones at the bottom of the board with the strategy AlphaGo was about to pursue. “Beautiful,” he said, then repeated the word several more times. This was not mere “tesuji”* - a clever play that can put an opponent off guard. This was a work of aesthetic as well as strategic brilliance, possibly even a "myoshu"*. Sedol continued to play nearly flawless Go, but it wasn’t enough to counter the striking creativity the DeepMind software displayed, even after move 37. By the end of the day the big news wasn’t that AlphaGo had won a second game, but that it had displayed such deeply human qualities - improvisation, creativity, even a kind of grace - in doing so. The machine, we learned, had a soul."
* A tesuji (手筋) is a clever play, the best play in a local position, a skillful move.
* Myoushu 妙手) is an "inspired move", a move which turns a game around or otherwise exceeds expectations.
(An excerpt from the book "Whiplash: How to Survive Our Faster Future" by Joi Ito and Jeff Howe - Page 239 - Description of the 2nd Go match between Lee Sedol (18-time world champion) and AlphaGo, an AI computer program developed by Google. It was played in Seoul, Korea in March 2016. AlphaGo won the series 4-1)
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