A game-changing result

IT WAS not quite a whitewash, but it was close. When DeepMind, a London-based artificial intelligence (AI) company bought by Google for 400m in 2014, challenged Lee Sedol to a five-game Go match, Mr Lee--one of the best human players of that ancient and notoriously taxing board game--confidently predicted that he would win 5-0, or maybe 4-1. He was right about the score, but wrong about the winner. The match, played in Seoul to crowds on the edges of their seats and streamed to millions online, was won by the computer, four games to one. Ever since Garry Kasparov, a chess grandmaster, lost to a computer in 1997, Go--which is far harder for machines--has been an unconquered frontier.