It’s official: the best Go player in the world is a program, AlphaGo

Go-playing program AlphaGo, developed by Google’s DeepMind, has secured victory against 18-time world champion Lee Sedol. AlphaGo won the first three games of a five game match played in Seoul, thus securing the match.



AlphaGo beats Lee Sedol, one the best Go players in the world

AlphaGo, the Go playing program developed by Google’s DeepMind, scored its first victory in the match against Lee Sedol.


This win comes in the heels of AlphaGo victory over Fan Hui, the reigning 3-times European Champion,  but it has a deeper meaning, since Lee Sedol is one of the two top Go players in the world, together with Lee Changho. Go is viewed as one of the more difficult games to be mastered by computer, given the high branching factor and the inherent difficulty of position evaluation. It has been believed that computers would not master this game for many decades to come.

Ongoing coverage of the match is available in the AlphaGo website and the matches will be livestreamed on DeepMind’s YouTube channel.

AlphaGo used deep neural networks trained by a combination of supervised learning from professional games and reinforcement learning from games it played with itself. Two different networks are used, one to evaluate board positions and another one to select moves. These networks are then used inside a special purpose search algorithm.

The image shows the final position in the game, courtesy of Google’s DeepMind.

Computers finally excel at Go



Go is a beautiful game, with a very large branching factor that makes it extremely hard for computers. For decades, playing this game well was outside the reach of existing programs.

We just learned that computers finally mastered Go, in a paper published in the journal Nature. By using machine learning techniques and, in particular, deep learning, the program AlphaGo, created by Google’s company DeepMind, managed to beat Fan Hui, the European Go champion, five times out of five. Whether AlphaGo is sufficiently strong to beat the best players in the world, remains to be seen. However, it already represents a very significant advance of the state of the art.

What was maybe the last bastion in table games still unconquered by computers is no more. Computers are now better than humans at all table games invented by humanity.