In this handout image provided by Google, South Korean professional Go player Lee Se-Dol (R) puts the first stone against Google's artificial intelligence program, AlphaGo, during the Google DeepMind Challenge Match on March 9, 2016 in Seoul, South Korea.
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March 9, 2016 9:55 AM EST

Google’s artificial intelligence program AlphaGo, a product of the company’s DeepMind unit, has just marked a significant achievement, beating the legendary Go player Lee Se-dol in a three-and-a-half hour game, the Verge reports.

Go, a Chinese board game that involves placing stones on a board to surround your opponent’s stones, presents a unique challenge to AI, as TIME wrote in January:

So it’s a big deal that AlphaGo was able to beat Lee, the first professional player ranked 9-dan (the top rank) it has ever played. “I was very surprised,” he said after the match, according to The Verge. “I didn’t expect to lose. [But] I didn’t think AlphaGo would play the game in such a perfect manner.”

The match was the first in a series of five, so Lee will get the his chance at revenge over the next week.

[The Verge]

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