A South Korean grandmaster of the ancient Chinese board game Go has scored his first win over a Google-developed supercomputer, a surprise victory after three humiliating defeats in a high-profile showdown between man and machine.
Lee Sedol thrashed AlphaGo after a nail-biting match that lasted for nearly five hours on Sunday in Seoul – the fourth of the best-of-five series in which the computer clinched a 3-0 victory on Saturday.
Lee struggled in the early phase of the fourth match but gained a lead towards the end, eventually prompting AlphaGo to resign.
Lee, 33, is one of the greatest players in the modern history of the game, with 18 international titles to his name – the second most in the world.
He earlier predicted a landslide victory over artificial intelligence (AI) but was later forced to concede that AlphaGo was “too strong”.
Lee had vowed to try his best to win at least one game after his second defeat.
The most famous AI victory to date came in 1997, when the IBM-developed supercomputer Deep Blue beat the worldchess champion Garry Kasparov.
But Go, played for centuries mostly in east Asia, had long remained the holy grail for AI developers due to its complexity and near-infinite number of potential configurations.
Demis Hassabis, the head of AlphaGo developer Google DeepMind, has described Go as the Mount Everest for AI scientists.
AlphaGo uses two sets of “deep neural networks” that allow it to crunch data in a more human-like fashion, dumping millions of potential moves that human players would instinctively know were pointless.
It also employs algorithms that allow it to learn and improve from matchplay experience.
Its performances during the games with Lee stunned many Go experts, who described its moves as so unconventional that no human player would ever make them.