A master of the ancient Chinese board game Go has retired from professional play after claiming artificial intelligence is "an entity that cannot be defeated".
Despite being the only player to ever win a game against AlphaGo under tournament conditions, the match finished 4-1 in the computer program's favour.
"With the debut of AI in Go games, I've realised that I'm not at the top even if I become the number one through frantic efforts," Lee told Yonhap news agency.
"Even if I become the number one, there is an entity that cannot be defeated."
The complexity of Go meant that many believed it would be impossible for artificial intelligence to master it, as it involves more configurations for pieces than there are atoms in the universe.
After AlphaGo's unexpected success three years ago, DeepMind has gone on to develop even more powerful artificial intelligence successors in the form of AlphaGo Master and AlphaGo Zero.
Lee's retirement ends a professional playing career spanning almost three decades that saw him become one of the most successful Go players of the modern era.
DeepMind founder and chief executive Demis Hassabis, who himself is an avid player of the game, congratulated Lee on a distinguished career.
"On behalf of the whole AlphaGo team at DeepMind, I'd like to congratulate Lee Se-dol for his legendary decade at the top of the game, and wish him the very best for the future," Mr Hassabis said.
"During the AlphaGo matches, he demonstrated true warrior spirit and kept us on the edges of our seats to the very end."
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