The game of Go 围棋
Go was born in China several centuries BC, under the name Weiqi 围棋, or "encirclement chess". It is a strategy game of immense popularity in the country, which then spread little by little across the world. It was in Japan that its name became Go 碁. Brought over by Chan Buddhist monks, it later reached Korea.
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This board scores by Chinese rules: each player's score is their territory plus their living stones on the board, and White receives a komi of 7.5 points. A stone played inside your own territory therefore costs nothing, and dead groups need no marking at the end of the game — they are captured on the board.
Native to the Far East, go 围棋 (囲碁 in Japanese) is the oldest abstract combinatorial strategy game known. Despite its great age, go still enjoys wide popularity in China, Korea and Japan. In the rest of the world, where it was discovered only recently, its reputation is growing too. Its success owes as much to the simplicity of its rules as to its combinatorial richness and its strategic depth.
Go sets two opponents against each other. They place black and white stones in turn on a board called a goban, and so try to control the playing area by building "territories". Each stone stands for a soldier; surrounded soldiers become prisoners.
The rules of go in brief
- The aim is to form territories — sets of empty intersections controlled by a player.
- Black starts by placing a stone of their colour on the empty grid. Players then take turns placing a new stone on an empty intersection of the board.
- A player may pass; but when both players pass one after the other, the game is over.
- Adjacent stones of the same colour are connected and form a group.
- The empty intersections next to a group are its liberties. If a player removes the last liberty, they take off — capture, or kill — the surrounded stone or group; that is atari. Recreating an identical earlier position is forbidden, however, and that is the ko rule.
- At the end of the game, each player's score is worked out. Prisoners — stones captured or dead — are placed on the intersections of the opponent's territory. One point is then counted for each free intersection: one prisoner or one point of territory is worth one point. The winner is the player with the most points.
The board
A game of go is played on a board, the goban, ruled with a grid of 19 horizontal lines by 19 vertical lines, giving 361 intersections. These standard dimensions are nonetheless often reduced to 13×13 and 9×9. Small boards are used mainly for learning and for quick games — though there is now a growing appreciation of play on these small boards.
The komi
Black, who plays first, has a built-in advantage. For centuries go was played without any compensation for this imbalance; Black's advantage was then assessed at five and a half points. White was therefore given that many extra points in games without handicap stones. This compensation is what is called the komi.
In recent years the komi has tended to rise: it has gone to 6.5 points in Korea and Japan, and even 7.5 points in China and in France.
In games with handicap stones, the komi is reduced to half a point. The half point in the komi makes drawn games impossible.
Legends of the origins
According to a Chinese tradition, it was two dragons named Hei-Zi (the black one) and Bai-Zi (the white one), arguing over which of them was the more powerful, who created weiqi — the Chinese name for go — to settle the matter. The gods then sent a third dragon to watch the game, ordering it not to come back and report until the game was over. Their rules were the same as ours today, except that the ko rule did not exist: being immortal, they were infinitely patient. So the dragons have been playing for thousands of years, and every millennium the gods send a new observer. At present five dragons are watching the game, and a sixth should be sent in a few years.
Computer go
Computer go has recently made great progress, thanks in particular to the Monte-Carlo method. Programs are able to hold their own against strong players on 9×9 boards.