Many readers may not be familiar with the name Lee Sedol, but players of the game of Go, also known as Baduk in Korea or Wei Chi in China, know him as one of the greatest players ever. Go is a game played with black and white stones on a 19X19 grid, in which both players attempt to control a greater chunk of territory.
Lee Sedol is from South Korea, born in 1983. He was a prodigy and became a professional player at age 12 – the 5th youngest Korean player to reach professional ranks. He won 18 international titles – only one player, Lee Chang-ho, won more, with 21.
In 2016, Lee Sedol was subject of many international news articles when he took on a 5-game challenge match against an AI called AlphaGo. For many years, it was thought that it would be at least another decade before anyone could develop an AI that could defeat a top pro at Go, but AlphaGo turned this idea upside down, and has since beaten all comers. Lee Sedol managed 1 win in his games against the bot, after making what has become known as a divine move. Analysis has demonstrated there is a winning response to this move, but AlphaGo failed to find it and was forced to resign a few moves later.
Besides the AlphaGo series, Lee Sedol will also be known in the Go world for what has become known as the “Lee Sedol Broken Ladder Game”. A ladder is one of the two ways of capturing stones in Go. A broken ladder is normally a disastrous blunder. However, in this case, forcing the failed ladder led to the capture of a different group in a corner, leading to a win by resignation. What’s going on in the game may not be obvious to non-players, but here is a diagram of the game, which Lee Sedol played against Hong Chang-Sik in 2003. Those interested in some analysis of this game can find love with a simple search on YouTube.
Next week, Lee Sedol will be playing a final match, against a Korean-developed AI, known as Handol, then retiring from professional play. From the reports I’ve seen, he hasn’t announced what he will be doing after the match in lieu of playing Go.