2006-04-28 newest contents, 2009-01-17 last update, 2006-04-28 first day, Robert Jasiek
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World Amateur Go Championship Rules - Informal Summary

Introduction

The World Amateur Go Championship Rules have been used since the First World Amateur Go Championship in 1979 on World Amateur Go Championships and on various other occasions. They are close to Japanese 1949 rules and also edited by the Nihon Ki-in. The rule text is shorter, concentrates on the rules of play, and uses less precedents. The original text is still very long (42 pages incl. diagrams) and thus has been summarized and reworded informally. Since the rules are not logical, go wisdom is a mandatory requisite for approximative understanding.

Rules

Go is a game for two players.
The game is played on a 19x19 grid board.
The players alternately play on empty board points with black starting.
The winner is the player with a higher territory count at the game end if the game does not end before without counting due to loss by resignation or exceeded time.
A komi game uses 5.5 points, handicap games use Japanese style.
A move surrounding opponent's stones removes them.
Removed stones become prisoners.
A move is forbidden if even after removal of opponent's stones own stones are surrounded.
A ko is a shape in which both players can alternately capture one stone.
A stone that has captured a stone in a ko may not be recaptured immediately.
At the game end stones are alive if a wise player could not see alternating play leading to removal.
Living stones of both colours are in seki if a wise player could not see alternating play leading to life of the stones of one colour independently of the stones of the other colour.
Not alive stones are dead.
A player may not pass until all neutral points and all necessary defensive moves inside territory have been played.
Two successive passes end the game.
At the game end dead stones are removed if they are surrounded by opponent's stones alive not in seki.
At the game end play in an alternating encore may remove dead stones in a seki if it remains seki.
At the game end after all removals territory on the board of a player is all empty points surrounded by his living stones not in seki and Japanese territory counting is performed adding prisoners and komi.
Doubtful cases concerning life, death, seki, necessity of defensive moves inside territory, counting of territory, positional repetition, etc. are to be settled in accordance with the Nihon Ki-in precedents.
Any doubtful case without a precedent shall be ruled upon by the Nihon Ki-in.

Nihon Ki-in Precedents

[At the game end a balanced double ko is a seki and it may not be used to avoid the game end by only playing within it.]

double ko seki [80]

[At the game end in a shape with possible repetitive play the stones of one colour are dead if wise alternating play could lead to their capture.]

double ko death [80]

If the players do not end the game by repeating positions, the game ends without result.

round-robin ko [80]; seki is also possible

round-robin ko [80]

triple ko [80]

triple ko [80]; seki is also possible

eternal life [80]; transformation to seki is also possible

[At the game end after hypothetical removal of all dead stones neutral points are empty points surrounded by living stones of both colours not in seki and defensive moves inside territory are moves that are necessary to maintain life of living stones, death of dead stones, and prohibit new opponent's living stones in own territory according to wise alternating play.]

neutral points (triangled), defensive moves inside territory (squared), dead stones (circled) [80]

a and b are neutral points. If white occupies a or b, then no defensive move inside territory on c is necessary, else it is. [80]

[80] The three-points-without-capturing positions shown in the diagrams below are treated as alive in seki at the game end. [No territory.]
[49] For the first three-points-without-capturing position white receives three points of territory [without performing capture and by means of prisoner stones], for the second and third five points each, for similar positions for each further black stone another two points.

three-points-without-capturing [80]

A bent four in the corner is independently dead, regardless of the rest of the board.

bent four in the corner [80]; black is dead

[80] [A game may not end if life and death depend on a direct ko.]
[49] A defensive move is required for a direct ko shape, when immediate means are available.

defense inside territory [80]; [80] : white need capture the single black stone; [49] : white need capture the single black stone, then connect the ko

defense inside territory [80]; ko need dissolution by either player

bent five in the corner [49]; a white defensive move capturing the single stone in the ko is necessary

bent six in the corner [49]; no white defensive move is necessary

defense inside territory [49]; a white defensive move is necessary

Before the game end in a thousand-year ko the player who is able to capture and connect the ko to retain a seki shall do so.

thousand-year ko [80]

[49] In the position below black has to capture one of the white strings and let the other one live.

a rare position [49]

Commentary

The original rule text is about ten times longer but does not contain much more contents than the summary except details of terms of play, handicaps, equipment, descriptions of eye, eye shape, etc., counting procedure and some referring diagrams.
The sources for precedents are [80] = English translation of the 1980 Second World Amateur Go Championship Rules by the Nihon Ki-in (the contents of the booklet of 1979 was the same); [49] = Nihon Ki-in 1949 rules
Only the [80] diagrams and texts are valid for the 1980 rules. [49] texts are valid for the 1949 rules. If both [49] and [80] are given, then [49] replaces [80] for the 1949 rules, else [80] is valid for them, too.
Bracketed [] text is interpretation only to ease access as to understanding.
Precedents are caused by historical incidents (like the Nobunaga triple ko) or rule disputes. They reflect the authority of the top Japanese go players (now the Nihon Ki-in) instead of simplicity and logic.
Since Nobunaga's death positional repetition due to play not in one ko has been considered evil. So despite the usage of the concept of "prohibition of positional repetition" in the original rule texts of Japanese 1949 and World Amateur Go Championship rules the void game precedents are enforced.
The knowledge of a go player of average rank has a closer insight in life, death, defensive moves inside territory, etc. than the original rule text allows. Therefore the summary uses "a wise player".
If a bent four in the corner were played out alternatingly, then a direct ko would result. By being ruled dead also this type of direct ko does not remain on the board like all other direct kos. The difference is that it can still be on the board at the game end only to be removed at the beginning of counting.
Normally, direct kos are to be resolved before the game end while indirect kos need not. Useful definitions do not exist. A defensive move is required to avoid any direct ko on the board or the possibility of wise alternating play (starting with either player) invariably leading to a direct ko. An indirect ko (approach-move ko, yose-ko) does not require a defensive move. (With Japanese 1949 rules defensive moves are not necessarily played before the game stop (start of confirmation of life and death filling neutral points and playing defensive moves) but are to be played until the game end (start of counting)).
Detailed remarks on the first diagram on defensive moves: [80] : defense inside territory; white need capture the single black stone [to make the ko about black's life "indirect" insofar as black needs to capture one ko stone before capture of another ko stone plays a direct ko for live; black need capture and resolve the ko to live; white's ko capture is direct due to possible directly following ko resolution; black's ko capture is direct due to possible directly following ko resolution; the original text would be insufficient and unclear if the [49] meaning were to be applied]; [49] : white need capture the single black stone, then connect the ko [or capture all the black stones; this avoids black from starting immediate means in that position by capturing the ko to enable the other ko being played as a direct ko for life]
A thousand-year ko as a whole is an indirect ko and at the game end would behave like a seki. The single stone in the ko, however, is considered dead and thus is required to be removed. At the game end a simple removal would leave unfilled points that could be filled maintaining seki. With the rules requiring alternate filling of neutral points this also applies here.
The original does not mention neutral points in seki. However, they need to be filled as far as possible. This does not apply for eyes etc. in seki.
In practice after a first pass the opponent could only not pass as well if he can play a so called one-sided dame.
The rules are close to the Japanese 1949 rules. That original has been even much longer. The game end has been simplified by requiring neutral points and defensive moves inside territory to be played before two successive passes, avoiding resumption even after two successive passes, and adapting the simplified game end to precedents. Three points without capturing has been altered as to assigned territory and a few precedents have been omitted.
The original does not clearly use passes but declarations of game end by the players, continuation in case of disagreement, and a definition of finished game; the passes have been added for simplicity.

Acknowledgement

To Juergen Mattern for donating literature to the library of the Go-Verband Berlin. To James Davies for providing the [49] diagrams and comments. (I will appreciate a copy or photocopy of the Nihon Ki-in 1949 or the Taiwanese 1952 rules incl. diagrams in any language.)