A world champion has retired because he has decided humans cannot beat computers his game. The grand champion is Lee Se-Dol South Korea. He was world champion the ancient, strategy board game Go. Some people compare Go to chess. Mr Lee is the only person the world to ever beat Google's AlphaGo computer algorithm. This is a special A.I. computer program created Google to play Go. Mr Lee, an 18-time world champion, told reporters earlier this week that: "Even if I become the number one, there is an entity that cannot be defeated. the debut A.I. in Go games, I've realized that I'm not the top even if I become the number one."
The game Go originated in China 3,000 years ago. Today, it is played mostly China, Japan and South Korea. It is believed to be the oldest board game the world. In 2016, the International Go Federation said it had 75 member nations, and that 46 million people worldwide knew how to play Go. Mr Lee started playing the age five. He turned professional seven years later, when he was 12. He played five games Google's AlphaGo and lost four them. He said his one victory was because a "bug" the program. The bug did not know what to do when Mr Lee made a "tricky" move. Today's Go programs are much more powerful than the one that beat Mr Lee.