“(Yonhap Interview) Go Master Lee Says He Quits—Unable to Win over AI Go Players”, Yonhap News Agency2019-11-27 ()⁠:

South Korean Go master Lee Sedol, who retired from professional Go competition last week after gaining worldwide fame in 2016 as the only human to defeat the artificial intelligence (AI) Go player AlphaGo, said his retirement was primarily motivated by the invincibility of AI Go programs.

“With the debut of AI in Go games, I’ve realized that I’m not at the top even if I become the number one through frantic efforts. Even if I become the number one, there is an entity that cannot be defeated”, he said in an interview with Yonhap News Agency in Seoul on Monday.

…But Lee said he managed to win Game 4 due to AlphaGo’s buggy response to his “tricky” moves. “My white 78 was not a move that should be countered straightforwardly. Such a bug still occurs in Fine Art (a Chinese Go-playing computer program). Fine Art can hardly be defeated even after accepting two stone handicaps against humans. But when it loses, it loses in a strange way. It’s due to a bug”, Lee said.

…“Frankly, I had sensed kind of a defeat even before the start of the matches against AlphaGo. People from Google’s DeepMind Technologies looked very confident from the beginning.”

…“Even with a two-stone advantage, I feel like I will lose the first game to HanDol. These days, I don’t follow Go news. I wanted to play comfortably against HanDol as I have already retired, though I will do my best”, he said.