Rules of Go
|
|
This is an in-depth discussion of the rules of Go.
Note: While the basic idea of go, conveyed by the outline rules given first, is not particularly complex, there are numerous subtle points which are not required study when first starting to play.
| Contents |
Players
Rule: There are the two players, called Black and White.
Go is a game between two players.
The equipment
The board
Blank_Go_board.png
Rule: Go is played on a board. The board is a grid of 19 horizontal and 19 vertical lines.
Beginners might prefer to play on a small board with 9 horizontal and 9 vertical lines (9 × 9 board). On this board learning tactics is easier and one is not confused by the complex strategies seen on big boards.
After having gained some experience (having played, say, 100 games), one can switch to the regular 19x19 board. Some teachers recommend moving up to a 13 × 13 board as an intermediate step, and this board is adequate for social players.
A point on the grid where a horizontal line meets a vertical line is called an intersection.
There are 361 intersections on the regular 19 × 19 board. In the following diagram, the mark (red circle) indicates one of the 25 intersections of the small 5 × 5 board: Template:Go board 5x5
(To save space, most diagrams show small boards. Here we have a 5 × 5 board.)
Stones
Rule: There are black and white stones.
The player Black uses black stones, the player White uses white stones. There is an arbitrary number of stones, i.e. the supply is unlimited. The diagram shows some stones on some intersections of the board: Template:Go board 5x5
The state of stones on the board
Chain of connected stones
Definition: A chain consists of one stone or of several stones that are of the same colour and mutually connected via lines of the grid.
This is a chain of 6 black stones: Template:Go board 5x5
Liberty
Definition: A liberty of a chain is an empty intersection adjacent to it.
The marked intersections (red circles) are the liberties of the black chain: Template:Go board 5x5
Removal
Rule: A play removes any opposing chains without liberty.
Before the play: Template:Go board 5x5
The play:Template:Go board 5x5
After the play:Template:Go board 5x5
In most cases, a play does not remove any chain. In other cases, a play might also remove a bigger chain, which consists of several stones. In yet other cases, a play might also remove two, three, or four opposing chains, if it takes away the last liberty of each of them.
Existence
Rule: A played stone exists on the board until the end of a game unless it is removed by the liberty rule.
Play
Alternate play
Rule: The players alternate. Black starts.
Before Black plays first, the board is empty:Template:Go board 5x5
Black makes a first play on one of the intersections:Template:Go board 5x5
Then White makes a second play somewhere:Template:Go board 5x5
The game will continue with Black and White alternating.
Play or pass
Rule: On his turn, a player makes either a play or a pass.
Normally, the player having the turn makes a play.
Empty intersection
Rule: When a player makes a play, he puts one stone of his colour on an empty intersection.
The following diagram shows how Black makes some play:Template:Go board 5x5
No Suicide
Rule: It is prohibited to place a stone where it would have no liberties (or be a part of a larger chain with no liberties). The exception is when the stone completes a capture of an opponent's chain.
[to be added: example with 1-stone suicide]
Note: Some Go rulesets allow suicide. The chain with no liberties is removed from the board.
[to be added: link]
Ko (no repetition of the same shape)
Goko.gif
Rule: If recapturing that stone would recreate the same board position from the previous move, the position is called ko, and the recapturing move is illegal.
To prevent endlessly repeating positions, the rule of ko prevents most plays that would repeat the previous board position. A player may not recapture on their next move and must play elsewhere (or pass). After a new move, the board position will be different, and the stone may then be recaptured.
Ko occurs when a stone has just been captured, and the stone which made the capture is left with only one remaining liberty.
The rule of ko is applied frequently (in most games), and often has a major or even decisive effect on the result. It is possible, but much less common (by a factor of 1000 or more) for other kinds of repetition to occur. Tournament rules make provision for what happens in these cases.
ko (more precisely kou) means "eternity" in Japanese, and is pronounced with a double length "o" sound.
Pass
Rule: When a player makes a pass, he does nothing. Alternation continues with his opponent.
End
Rule: Alternate play ends when a player makes a pass and then his opponent immediately makes a pass.
Note: Some Go rulesets use other rules to end alternate play.
[The below is under construction.]
When both players have passed, the game has ended. Dead stones (those that remain on the board but cannot avoid capture) are now removed as if they were captured. Most rule sets allow disputes over the status of chains and loosely-connected groups of chains to be resolved simply by continuing play until both players are agreed. The Japanese rules, instead, have a long list of exceptions and precedents that are referred to in tournament play. Most players remain unaware of these complications in the Japanese rules for the vast majority of their games.
After dead stone removal, counting begins to determine which player is the winner with the greater share of the board. There are two methods of scoring. In the Japanese, or territory scoring method, each player scores the number of empty intersections he has enclosed, and subtracts the number of captures taken from him (this is done easily by placing the captures taken from a player into their empty intersections to reduce the score). In the Chinese, or area scoring method, captures are not scored, but a player scores for every intersection that he controls -- that is, all points where he has placed a stone or that are completely surrounded by his stones.
Whichever scoring method is used, the player with most points wins. In normal circumstances, the Chinese and Japanese scoring methods give the same winner.
Winner
Rule: When alternate play has ended, the winner is the player whose stones surround more territory (empty intersections on the board)
Note: Many Go rulesets, in particular Chinese rules, use other rules to define the winner. However the result (win or loss) is usually the same under all rulesets.
[to be added: link]
Optional Rules
Compensation
To allow players of different skills to compete fairly, handicaps and komi are used. These are considered a part of the game and, unlike in many other games, they do not distort the nature of the game. Players at all levels employ handicaps to make the game more balanced.
Komi
In an "even", or non-handicap game, Black's initial advantage of moving first can be offset by komi (compensation points): a fixed number of points, agreed before the game, added to White's score at the end of the game. The correct value of komi (to properly compensate for Black's advantage) is controversial, but common values are 5.5, 6.5 or 7.5 -- the fractional value avoids a tied game. In a handicap game, komi is usually set to 0.5 (i.e. White wins if the game is tied). A handicap game with a handicap of 1 starts like an even game, but White receives only 0.5 komi (i.e. a White player who is stronger by one rank is handicapped only by Black's first-move advantage).
Handicap
Handicaps are given by allowing the weaker player to take Black, and declaring White's first few moves as mandatory "pass" moves. In practice, this means that Black's first move is to place a set number of stones (usually the number is equal to the difference in the players' ranks) on the board before allowing White to play. Traditionally, the "star points" -- strategically-important intersections marked with small dots -- are used to place these handicap stones. On the 19x19 board, there are nine star points: at the four 4-4 points in the corners, at the four 4-10 points along the sides, and one at the 10-10 point (the centre of the board, or tengen in Japanese). Other board sizes do not necessarily have marked star points.
When Black is only one rank weaker (also known as one stone weaker, due to the close relationship between ranks and the handicap system) he is given the advantage of playing Black, but without any mandatory White passes. For rank differences from two through nine stones, the appropriate number of handicap stones are used. Beyond nine stones, the difference in strength between the players is usually considered great enough that the game is more a lesson, with White teaching Black, so nine stones is the nominal upper limit on handicap stones regardless of the difference in rank (though higher numbers of stones, like thirteen or seventeen, can be given if the teacher wants more of a challenge).
Also see Go handicap.
Thinking times
See the Timing section of the main Go article.
Tournament systems
[to be added]
Strategy and Tactics
Sample game
See a sample game, on a 9x9 board, by two professional players.
Rule Sets
There are many official rule sets for playing Go. These vary in significant ways, such as the method used to count the final score, and in very small ways, such as whether the two kinds of "bent four in the corner" positions result in removal of the dead stones automatically at the end of the game or whether the position must be played out, and whether the players must start the game with a fixed number of stones or with an unbounded number.
Rule sets include AGA (American Go Association), Chinese, Japanese, Korean, French, New Zealand, and various modifications such as those for simple games, IGS (Internet Game Server), Ing Chang-Ki's rules, etc.
Further detailed information may be found at the following external links. Note that no one link has a complete list of all commonly used rule sets, and most of these links do not have complete information any one rule set. However, full information can be found by traversing links located at these Web sites.
External Rule Set Links
- http://home.snafu.de/jasiek/bascomp.html
- http://www.usgo.org/resources/internet.asp#Rules.
- http://kgs.kiseido.com/en_US/help/ruleSets.html
- http://senseis.xmp.net/?RulesOfGo
- http://brooklyngoclub.org/jc/rulesgo.html (simple rules useful for the mathematical analysis of Go)
- http://home.snafu.de/jasiek/rules.html
- http://wwwhomes.uni-bielefeld.de/achim/go_rule_philo.html
eo:Ses Reguloj de Goo nl:spelregels van Go pl:Zasady go
See also
See also: Go, Go strategy and tactics, Go concepts