To prevent cycles, one might argue that traditional go rules already serve the purpose. Simple ko rule prohibits cycle within 1 turn (with each player playing once) and superko rule prohibits longer cycles. Why do we need something different? The rationale of each component of Kee Rules is illustrated as follows.

A. Why is the cyclic prohibition superko (rather than simple ko) in nature?

Cycles like 3-ko, 4-ko and chosei can be longer than 1 turn. Superko can provide a sensible resolution to these long cycles.

B. Why is the cyclic prohibition positional in nature?

A good rule shall penalize the one who produces the repeated board position. Consider a 3-player game with "Board A -Player 1-> Board B -Player 2-> Board A -Player 3-> Board A -Player 1-> Board B". It is more reasonable to prohibit "Board B -Player 2-> Board A" (if positional) than to prohibit the second "Board A -Player 1-> Board B" (if situational).

C. Why is the cyclic prohibition lifted after a pass play?

This is to draw consistency between a non-fully-occupied board and a fully-occupied board. In a non-fully-occupied board, to a player who has just occupied a ko position but actually hopeless to take further step on it, an irrelevant play on elsewhere on the board by his opponent can already be treated as a effective ko-threat to him because the board position has been altered. As the hopeless player finds no way to take further step on it, the opponent can take back the ko position and win the ko.

However, in a fully-occupied board, no where on the board is available for the opponent to make such a irrelevant ko-threat play. If cyclic prohibition cannot be lifted by a pass, i.e. a pass is not assumed to have altered the board position or treated as the weakest ko-threat, the ko position would be forever occupied by the hopeless player and the game would be halted there. This is inconsistent with the non-fully-occupied board and undesirable.

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Sending Two Returning One

Also consider this "sending two returning one" situation where Black keeps playing as a cycle after White has already passed (in White 2). If the cyclic prohibition is not lifted, wrong timing of cycle (White 4 instead of Black 5) would be prohibited.

D. Why does the game end when the same player passes on the same board position again?

After a pass play, the player is free from any previous cyclic prohibition. If the same player passes on the same board position again, there is actually no change in both board position and prohibition status (i.e. free from any previous cyclic prohibition) from the previous identical pass play. The game can end without any complaint because any desired possibility should have already been be tried out after the previous identical pass play.

E. Why are all the board positions consecutively passed by all players considered as the scoring board positions?

If there is any stone play after the initial scoring play, the result of the game is cyclic in nature. Instead of putting all weights to the single final board position which is just one within a cycle of many board positions, it is reasonable to allow certain board positions within the cycle to be used for scoring.

It is easy to understand that board positions which are not consecutively passed by all players should not be used for scoring. It is because there is at least one player does not agree on such board position to be used for scoring by successfully making stone play on it.

On the other hand, a player passes on a board position either because he agrees on such board position to be used for scoring, or is forced to pass because of cyclic prohibition. As the end of a game means the desired possibility has been tried out, a player forced to pass will still be forced to pass next time even if the game continues. In such case, the player cannot say he does not agree if situation does not allow. Therefore, all the board positions consecutively passed by all players can be considered as the scoring board positions.

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II. STRENGTHS OF KEE RULES

4. Compatible no matter whether suicide is allowed (suicide is not allowed in the following rules as default).

5. Compatible with both area and territory scoring systems (area scoring is chosen in the following rules as default).

III. CONTENTS OF KEE RULES

1. A board consists of intersections, where intersections are adjacent to some of the others in a pre-defined way. In usual circumstances, a board is marked with 19 parallel vertical lines and 19 parallel horizontal lines, making 361 intersections.

2. The number of stones shall be sufficient to end a game. In a two-player game, usually lens-shaped black and white stones are used.

3. During a game, each player possesses one color of stones.

4. In usual circumstances, a game starts with an empty board, where all intersections on the board are unoccupied.

5. Each player makes a play by alternately placing one stone on an unoccupied intersection of the board ("stone play") to occupy such intersection. In a two-player game, usually black player makes the first play, then white player, and then black player again and so on in alternation until the end of the game.

6. After a stone has been placed on the board, it cannot be moved to any other intersection.

7. A stone play is the right of a player. In any play, a player can give up the right of a stone play and choose to pass instead ("pass play").

8. An unoccupied intersection which is adjacent to a stone on the board is called the liberty of such stone.

9. When a stone is adjacent to another stone of the same color, these two stones are connected and belong to a single stone unit, and the liberty of any one of these stones is considered to be the liberty of the whole stone unit.

10. For any stone unit, when an opponent stone is placed adjacent to it, such opponent stone takes a liberty away from it. When all the liberties of a stone unit have been taken away and no liberties are left, such stone unit has to be removed from the board.

11. A stone unit without liberties is removed from the board. There are two cases:

(a) When a stone is played so as to take the last remaining liberty of any opponent stone unit(s), all those opponent stone unit(s) is/are immediately removed from the board.

(b) When a stone is played so as to take the last remaining liberty of any opponent stone unit but would also leave the newly formed stone unit with no liberties, only all those opponent stone unit(s) is/are immediately removed from the board and the newly formed stone unit is not removed.

12. A forbidden intersection of a player is an unoccupied intersection on the board which, if occupied by a stone of such player, would leave the newly formed stone unit with no liberties but fail to take the last remaining liberty of any opponent stone unit(s). A player may not place a stone on a forbidden intersection.

13. A player may not make a stone play to produce a board position which would be identical to a previous board position unless a pass play has ever been made by any player after the last such previous board position.

14. The game ends when the ranking can be agreed by all players.

15. The game also ends when a player makes a pass play on a board position which he has previously made a pass play on. The series of plays after but not including such previous pass play is called the "scoring cycle".

16. At the end of a game where ranking cannot be agreed by all players, the ranking would be determined by scoring.

17. For the scoring cycle, if any stone play exists, the series of all pass play(s) before the first such stone play, if any, is repositioned to follow the last play. A board position which has been consecutively passed by all players in the scoring cycle after such reposition, if any, is called a �gscoring board position�h.

18. For each scoring board position:

(b) With respect to each player, the intersection(s) occupied by the stone(s) of such player on the board, as well as the unoccupied intersection(s) which is/are fully enclosed by such stone(s), is/are counted towards the point(s) of such player.

(c) Unoccupied intersection(s) which is/are enclosed by stones of different players on the board are not counted towards the point(s) of any player.

19. If there are no scoring board positions after the game has ended, the game is draw.

20. The ranking is determined according to the average of total point(s) earned by each player from each of the scoring board position(s). The higher the point(s) earned by a player, the higher is the ranking.

IV. TYPES OF CYCLES

Type 1

Type 2

Examples: 2x1 board, 2x2 board, 2x3 board, some players disturbing on a fully occupied board, 1x8 board (see below)

V. TYPES OF CYCLIC PROHIBITIONS

A. Simple ko

Too weak to disallow all kinds of long cycles (all long cycles concluded as "no result").

B. Superko

C. Spight Rules

Spight Rules give scores to type 2 using the single last board position upon game termination despite the fact in some situation that such single board position was just one within a cycle of many board positions.

D. Kee Rules

Kee Rules give scores to all types. Type 2 is given a definite score by "cyclic scoring" which considers the board positions passed by all players during the cycle.

I. JUSTIFICATION OF KEE RULES

A. Why is the cyclic prohibition superko (rather than simple ko) in nature?

B. Why is the cyclic prohibition positional in nature?

C. Why is the cyclic prohibition lifted after a pass play?