Spight Japanese style rules

    Keywords: Rules

Bill: Why a new set of Japanese style rules? The Japanese '49 rules codified traditional rulings for several special cases and were criticized for being ad hoc. The Japanese '89 rules got rid of ad hoc rulings, but redefined life, death, and seki in terms of virtual play that was unclear and difficult to understand. They also introduced the antiseki, in which dead stones are not removed from the board. They also provided for cases where both players lose, but the official commentary showed how to score such positions. Since then, a new kind of rules anomaly has been found, based upon the redefinition of seki. IMO, the current Japanese rules are not suitable for amateur play. (The pros can fend for themselves.)

My aim is to revise the Japanese rules to provide for an actual encore rather than virtual play, in a way that is clear and easy to understand. What I propose is similar to Ikeda Territory rules II, but with results that are closer to those of the current Japanese rules.

N. B.: I found a significant flaw in the first version of these rules as a model of the Japanese rules. (See the Bent Four lives again example in the commentary.) I have made revisions, incorporating the pass for ko rule. I have added a rule to mend its flaws, that allows a player to take the same ko (in a global sense) only once. In effect, then, the player who takes a ko is its komaster. I am trying to keep the rules as close to the theory of evaluation as I can.


Article 2. The Play

The pieces are called stones. One player plays the black stones and the other player plays the white stones. The players take turns playing one stone at a time on the board. At her turn a player may pass instead of making a play.

Comment: The current article does not mention passes.

Article 6. Ko

A shape in which the players may alternately take and take back a single stone of the opponent is called a ko. A player whose stone has been captured in a ko may not take the ko back on her next turn.

Comment: The Japanese rules do not consider a pass a play. By saying turn rather than play or move, this article allows a player to take a ko back in the encore after passing. That possibility means that kos should be settled before the encore, to prevent recapture after a pass. The '49 rules required kos to be settled, and the '89 rules have the same effect.

Article 7. Life and Death

When play is paused according to Article 9.1, the players may agree about which stones on the board are dead, if any. If they do so, those stones are dead and all other stones on the board are alive. Dead stones are removed without further play.

Comment: This article gives human, operational definitions of life and death. I think that the way the Japanese rules attempt to define life and death generates problems and potential confusion. The original article also gives the ko rule for virtual play. That is addressed in the encore article, for clarity.

Article 8. Territory

After all dead stones, if any, have been removed, empty points that are surrounded by stones of the same player are called eye points, and any empty points that are not eye points are called neutral points. All stones that surround the same eye points belong to the same group. A group is called a seki group if it adjacent to a neutral point, or if one or more of its stones is in atari. Eye points that are surrounded by a group that is not a seki group are territory. Territory belongs to the player whose stones surround it.

Comment: The current definition is unclear. First, it distinguishes eye points from neutral points, and later distinguishes some eye points from territory in an unclear way, talking about seki stones possessing neutral points that they are not connected to. I replace the idea of seki stones with that of a seki group, and include the idea of atari, to cover double ko seki and other strange seki.

Article 9. Rounds, Encore, and Game End

1. Rounds

There may be more than one round of play. Each round ends in the following way. During the round one player (the Passer) passes in a certain position of the whole board, and later the other player (the Repeater) repeats that position. The repetition may occur by a pass or by a play. The repetition need not occur on the next turn.

When the round ends, unless the game ends without agreement as provided in section 3, the Passer may start the next round immediately by making a play, or she may pause play for agreement about dead stones. (She may not pass now without pausing play first.) During the pause she takes a few seconds to indicate which of her stones, if any, she considers to be dead. She may say that she has no dead stones. Then the Repeater takes a few seconds to agree or to ask that play resume in the next round. If the Repeater asks that play resume, the Passer starts play in the next round. If the Repeater agrees about the dead stones, she takes a few seconds to indicate which of her stones, if any, she considers to be dead. Then the Passer takes a few seconds to agree or to resume play in the next round. If both players agree about which stones are dead, the game ends.

2. The Encore

The first round of play is called the play. If the game does not end at the end of the play, there is an encore consisting of one or more rounds of play. There are special rules for play in the encore. Let us call the first player in the encore Player A and the second player Player B.

a. Pass Stones

If a player passes during the encore she gives the opponent a stone as a prisoner. If Player A has the last turn of the encore, Player B gives Player A a stone as a prisoner.

b. Ko rules

1. At the start of the encore there is no ko ban.

2. A player may take a specific ko in a particular position of the whole board only once.

3. A player may take a ko back only after passing for that ko.

Comment: In effect, there are no ko threats, not even local threats, and the player to take a ko is its komaster. The pass for ko rule prevents the opponent from taking the ko back without allowing the player who took the ko to make another play in the ko. The once only rule forces her to make that play while she can.

Rule 2, the once only rule, may sound difficult to apply. However, with rare exceptions, if any, the only positions to worry about are those reached by a sequence of ko plays.

3. Ending the Game

If the players agree about dead stones at the end of a round of play, as provided in section 1, the game ends.

If a round of play ends in a position where a previous round ended, the game ends without agreement. All stones on the board are alive.

Comments: This article has been completely rewritten. It also breaks new ground for me, with provisions for agreement about dead stones. As we know, it is possible to write rules without such provisions, allowing players to reach agreement informally. And informal agreement works in the vast majority of cases. However, in recent years misunderstandings about ending play have created problems in tournament games under both Japanese and Ing rules. So I felt that laying out a clear procedure was a good idea.

One problem with reaching agreement at the end of play is that a player's view of the position may improve and alter her play in the encore. The Japanese '89 rules address that problem with the both lose article, and with resuming play by the opponent of the player who requests it. Since an encore may be necessary in any event, it should just start with the player whose turn it is.

These procedures are aimed at keeping discussion to a minimum. A round may start without any attempt at reaching agreement. If the player does seek agreement, she indicates which of her own stones are dead. That way she does not telegraph to her opponent which of her opponent's stones she thinks are dead.

The phrase for a few seconds indicates that the agreement procedure is not a time for cogitation. If there is any doubt about life and death, play should continue.

For more explanations see the commentary.

Article 10. Determining the Result

1. If both players agree about the dead stones, the game ends and the dead stones are removed as prisoners without further play. Then territory is determined according to Article 8.

If there was an encore and the player who had the first turn in the encore also had the last turn, that player receives a stone as a prisoner.

If there are one or more stones on the board in a seki group which were played during the encore, the players give one stone as a prisoner for each such stone they played.

{The rest of the article is the same.}

Article 12. No Result

During a round of play, if a sequence of plays repeats the same position of the whole board without ending the round, the players may agree to end the game without result. If they do not agree, but repeat the same position again by a sequence of plays, the game ends without result, anyway.

Comment: A position may repeat if there is an intervening pass or if the repetition ends the round.

Article 13. Both Players Lose


Bill: Well, that is the second version. I have added a commentary based upon the official Japanese commentary.

Questions and Comments

Please let me know your questions and comments in this section. My intention is to provide a workable set of Japanese style rules. I am especially interested in ease of understanding and application. I do not prefer these rules and will not debate their philosophical flaws. I am writing them for amateurs who want to play by Japanese style rules.

RobertJasiek: You might wish to notify me when your rules will be stable. What do you think of my Intermediate Step Rules? Is it not workable?

Bill: Do you mean your 2004 rules? I think that you take an interesting approach. The J89 rules are quite unclear. As for whether average go players find your rules easy to understand and apply, that is not for me to say. I am too close to these questions to tell. That is a major reason I would like feedback about these rules.

RobertJasiek: I mean the Intermediate Step Rules in my "Commentary on the Japanese 1989 Rules". See the section "Proposals for Future Revisions | Intermediate Step - Rules".

IanDavis: What is the effect of simply using Superko, but with the caveat that where a whole board position (board state) is recreated through the capture of more than one stone, superko does not apply. Theoretically send two receive one could continue for ever here - but this would be idiotic since one player would no longer be able to win after about 50 repetitions. Thus this would be equivalent to simply placing stones in your opponent's territory.

RobertJasiek: a) You mean: more than two stones. Capture and repcapture of a single stone in a basic ko are already 2 stones. b) Your rules construction allows intevening passes in between capture in a basic and potential recapture. This is somewhat useless though since a 1-eye-flaw will remain on the board. So why don't you take the basic ko rule "Recreating is prohibited after a succession of two board-plays? c) You do not say what shall happen in case of a cycle with too many but an equal number of stones captured in it. Ok, let me propose you want the game to end as a tie then. This also answers your question what happens then. d) Now we can start looking at the interaction with the rest of Spight-Japanese-style rules. - EDIT: Ah, maybe you mean that the capturing board-play that would recreate the position captures more than one stone? If so, then we need to make a classification of various cases and study each...

IanDavis No I don't mean more than 2 stones.

RobertJasiek: Please precisely formulate what you mean then.

IanDavis: It's quite clear at the moment.

Herman: What about Eternal Life?

IanDavis: That would seem unchanged if a modified superko rule was used, haven't time to look at how Spight handles it :)

Bill: One place that these rules differ from the official rules is that the official rules allow sending-two-returning-one to go on indefinitely, while in these rules the repetition after a pass ends the round. Eternal life is treated the same under both.

Willemien: The rules here are incomplete, where can I find the complete rules?

Bill: [ext] Nihon Ki-in 1989 rules

Spight Japanese style rules last edited by tapir on April 10, 2013 - 01:30
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