Rules of Go
From Free net encyclopedia
68.6.112.70 (Talk | contribs)
/* Alternate play */ -> turn based
Next diff →
Current revision
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 |
Basic Rules
Players
Rule: There are the two players, called Black and White.
Go is a game between two players.
The equipment
The board
Image: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 unlimited supply of stones. 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 | Black plays | After removal |
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 is existent on the board until the game's end, provided it is not taken in a removing play (at which point it becomes nonexistent).
Play
Turn-based play
Rule: The players alternate. Black starts.
Before Black plays first, the board is empty. Black makes a first play on one of the intersections. Then White makes a second play somewhere:
| Start | Black plays | White plays |
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 or she puts one stone of his or her colour on an empty intersection.
The following diagram shows how Black could make a 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)
Image: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.
This "basic ko rule" is adequate for the simplest kind of ko, which occurs when two single stones could otherwise recapture each other indefinitely. This situation occurs in most games and often has a major or even decisive effect on the result. To prevent endless repetition, the rule of ko forbids 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.
Other positions which could lead to an endlessly repeating position are rare enough that many frequent players never encounter them; their treatment depends on what ruleset is being used. Under some rulesets, such games may be considered drawn if neither player opts to escape the loop by playing elsewhere (as a player with an overwhelming lead might be inclined to do). The AGA and New Zealand rule sets have a "superko" rule forbidding any move that repeats any previous board position. The Ing rules feature a complicated distinction between "fighting" and "disturbing" ko.
The word ko (Japanese: 劫 kō; usually written with katakana コウ) means "eternity" in Japanese [1], and is pronounced with a double length "o" sound.
Pass
Rule: When a player makes a pass, he or she does nothing. Alternation continues with his or her 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 settle questions of life or death by hypothetical play under different ko rules than those used during regular play.
Winner
Different scoring rules coexist. Choose one of them before playing. In practice they will almost always determine the same winner.
Area Scoring Rule: When alternate play has ended, each player's score is the number of his stones on the board plus the number of empty intersections surrounded only by his stones. This method is also called "Chinese scoring".
Traditional Territory Scoring Rule: When regular alternate play has ended, each player's score is the number of empty intersections surrounded only by his stones (called "territory"), minus the number of prisoners taken from him. (Customarily, the prisoners are used to fill in some of the territory of the player they were taken from, just before counting the territory.) Before the numbers of empty intersections surrounded only by his stones are determined, any opposing stones that could be captured by strategically perfect hypothetical alternate play are called "dead" and are removed without approaching their liberties. The prisoners are the stones captured during regular alternate play or removed as dead after the end of regular alternate play. Also called "Japanese scoring", this method typically differs from the other two by at most one point.
Territory Scoring Rule with Pass Stones: Whenever a player passes, instead of playing on the board he pays one of his own stones. Alternate play ends with two passes, after which players try to agree on which stones are "dead"; if they cannot agree, they resume play. The agreement process is terminated by either complete agreement on all groups, or four consecutive passes; then, if the last pass was by Black, White must pass one more time to equalize the number of stones played by each. Finally, each player's score is his "territory" minus the number of prisoners taken from him (again, the subtraction can be done by filling in prisoners). Prisoners are the stones captured during alternate play, removed as dead, or paid for passing. This is part of the American Go Association rules; the extra complications serve to make this method give results precisely equivalent to area scoring.
Whichever method is used, the player with the higher score is the winner.
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 hoshi ("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). Smaller boards such as the 13x13 and 9x9 also have star points. The 13x13 has 9 at the 3-3 points, 3-6 points, and the center. The 9x9 board has only 5 points: the 3-3 points and the center.
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 or she 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, up to 41 stones in some cases, 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
The rules in a tournament aren't optional during a tournament. But you can choose to use the Tournament rules during a normal game or a handicap match.In a tournament there are different age divisions ->usually 7-10,11-14,15-20,21-26,27-35 BUT, if you are in a national or inter-continental tournament, there are usually only 3 age groups.
Variations
Go is an ancient game and as such the rules are not entirely set in stone. The two main variations in use today are the Japanese-style ruleset and the Chinese-style ruleset (the description above is for the Japanese rules).
Scoring
The defining difference between rulesets is the scoring method: territory scoring (Japanese), where a player's score is determined by the number of empty locations that player has surrounded minus the number of stones their opponent has captured; and area scoring (Chinese), where a player's score is determined by the number of empty locations that player has surrounded plus the number of stones that player has on the board. If the game ends with both players having passed the same number of times, then the difference between their scores will be identical under both scoring methods (ignoring aspects of tradition where there is further difference between the major rulesets in this regard).
The tradition of dead stone removal (where certain outcomes can be agreed upon without being played out) is notably more complicated under Japanese-style rulesets where stones are removed and territory counted (or not) even though such an outcome could not be reached under normal play.
Repetition
The major division in rules to prevent repetition is between the simple ko rule and the super ko rule: the simple ko rule (typically part of the Japanese ruleset) prevents repetition of the last previous board; while the super ko rule (typically part of Chinese derived rulesets) prevents repetition of any previous board. The super ko rule is further differentiated into situational super ko (includes whose turn it is) and positional super ko (ignores whose turn it is). The simple ko rule (contrary to the name) generally includes additional rules to handle other undesirable repetitions (e.g. long cycles can lead to no result where the game must be replayed).
Suicide
Currently most major rulesets forbid playing such that a play results in that player's own stones being removed from the board, however some rulesets (notably, New Zealand derived rules) allow suicide. Sometimes suicides can be used strategically to win a large area or territory versus the alternative of neither player getting anything or for both to be in a standstill.
Compensation
The major rulesets differ in how handicap stones are placed on the board: free placement(Chinese), where stones can be placed anywhere (as if the player's turn repeated); and fixed placement(Japanese), where tradition dictates the stone placement (according to the handicap). Area scoring rules and territory scoring rules also differ in the compensation given for each handicap stone (since each handicap stone would count under area scoring). Komi (compensation for going first) also varies, ranging from several fixed values (commonly 5.5, 6.5, or 7.5) to various meta-games to determine a value (notably Auction Komi).
Board Sizes
Most Go is played on a 19x19 board, but 13x13 and 9x9 are also popular sizes. Historically other board sizes were commonly used (notably 17x17, which is thought to have evolved into the current 19x19 board). Go is also sometimes played on various novelty sized boards (usually very large). Generally all rules apply to all board sizes, with the exception of handicaps and compensation (whose placement and values vary according to board size).
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 on any one rule set. However, full information can be found by traversing links located at these Web sites.
See also
External rule set links
- http://home.snafu.de/jasiek/bascomp.html
- http://www.usgo.org/resources/internet.asp#Rules.
- http://www.britgo.org/rules/compare.html (table comparing aspects of several rulesets)
- 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
- http://www.cwi.nl/~tromp/go.html (Tromp-Taylor ruleset)
eo:Ses Reguloj de Goo fr:Jeu de go nl:spelregels van Go pl:Zasady go