Triple Ko

Sometimes a game played under Japanese rules ends in Triple Ko (三劫). Below some examples of the types of situations involved.

(It is said that the Chinese rules include a superko rule that settles all complicated repetitions, so that there would be nothing special about triple/quadruple ko and the like under Chinese rules. In practice however, it seems the Chinese follow the Japanese and declare a game "Void", "No Result", when such repetitions occur.)

See also Quadruple Ko and Eternal Life.


Games ending with "No Result" because of a triple ko:

Black White Date SGF
Nagano Kaizen(?) Inoue Shunseki 1724-04-27 sgf *
Sugiyama Chiyosaburo Toya Dowa 1838-04-13 sgf *
Takashio Kenji Yamaki Chinpei 1849-09-18 sgf *
Kaji Kazutame Watanabe Hideo 1953-08 sgf *
Cho Chikun Fukui Masaaki 1970-09-16 sgf *
Sugiuchi Masao Hoshino Toshi 1975-01-16 sgf
Kato Masao Cho Chikun 1975-07-10 sgf *
Yanagawa Hiromasa Matsuoka Akira 1980-05-28 sgf *
Lee Sedol Lee Hyung-ro 1997-04-15 sgf *
Cho Chikun O Rissei 1998-10-14,15 sgf *
Yoda Norimoto Hikosaka Naoto 2002-05-09 sgf *
So Yokoku Zhu Songli 2006-04-17 sgf *
anon. anon. 2006-10-20 sgf *
He Xin Zhang Chao 2008-07-17 sgf *
Gao Xing Pan Yang 2009-05-14 sgf *
Kim Hyeongwoo Heo Yeongho 2009-11-23 sgf *
Lee Wondo Lin Shuyang 2010-08-05 sgf *
Kim Yoonyoung Yoshida Mika 2010-11-23 sgf *
Li Zhe Gu Li 2011-09-04 sgf *
Liu Jianchang Chen Qingyu 2012-04-16 sgf *
Yamashita Keigo Kono Rin 2013-09-27 sgf *
Chen Yaoye Gu Li 2013-11-02 sgf *
Meng Tailing Kim Hyeongwoo 2014-08-04 sgf
Shin Jinseo Kang Yutaek 2015-09-20 sgf
Park Taehee Kim Dayoung 2017-03-07 sgf *
Li Qincheng Chen Xian 2018-05-16 sgf

Additions and corrections are welcome. Mail to

One dead group and a group with three false eyes

Cho Chikun vs. Fukui Masaaki, 1970-09-16

triple ko sgf

It is Black's turn. As soon as White has a free move, she will play C19 and capture the Black group. So Black is forced to take one of the three kos, and then White takes another and a cycle is forced.

Another example:

Lee Sedol vs. Lee Hyung-ro, 1997-04-15

triple ko sgf

It is White's turn. As soon as White has two free moves, she will play K10 and G4 and capture the Black group. After one free move, a cycle is forced.

Two groups with a common ko and a further false eye each

Sugiyama Chiyosaburo vs. Toya Dowa, 1838-04-13

triple ko sgf

Here Black has just captured at O19. White has no choice but to capture at S19. If Black connects, or plays tenuki, White takes at N19 and captures the Black group. So, probably Black has to capture at L15, White at N19, Black at R19, White at L16, Black at O19 and after six moves the situation repeats.

Both players have the option of using external ko threats, and giving up their group in return for two unanswered moves elsewhere.

Another example:

Li Zhe vs. Gu Li, 2011-09-04

triple ko players sgf

Here White has just captured at G19. The situation is similar to the previous one, but the groups are bigger, so it will be more expensive to break out of the cycle.

Yet another example (which inspired the Hikaru-no-go episode shown next to it):

Nagano Kaizen vs. Inoue Shunseki, 1724-04-27

triple ko hikaru-no-go sgf

Note that the Hikaru version has a quadruple ko.

Two 1-eye groups with a common ko and a further false eye each

Kato Masao vs. Cho Chikun, 1975-07-10

triple ko sgf

Here White has just captured at J19. If both players are happy with the outcome, they can take the three kos in turn and get a Void result. Black has no choice, but White can deviate, if he wants.

Suppose that at some point after White has captured at T17, he fills at T16. A fight between two groups, each with one eye and a common ko, where one has an additional outside ko is always won by the group with outside ko - that group can always maintain two liberties by taking one of the kos, while the other needs infinitely many external ko threats.

That means that at the moment White fills at T16, Black must make sure to destroy White's eye by capturing at L18. That again means that Black K16, White T17, Black P19, White T16 is lost for Black, and also Black L18 loses, so that Black has to play P19. After White T17, Black K19, White can choose to fill at T16. Now Black captures at L18, White at Q19, and White wins unless Black has two threats that cannot be ignored and ignores two White threats himself.

In the present game that was a real possibility and White (Cho Chikun) chose the Triple Ko outcome.

Another example:

Yanagawa Hiromasa vs. Matsuoka Akira, 1980-05-28

triple ko sgf

Here Black has just captured at A7. White has an outside liberty and can win (by filling at F1) if he is able to ignore two Black threats. Black has no choice.

Another example:

Yoda Norimoto vs. Hikosaka Naoto, 2002-05-09

triple ko sgf

Here White has just captured at S1. There are no outside liberties, and neither player has a choice.

Three further examples:

Takashio Kenji vs. Yamaki Chinpei, 1849-09-18
Gao Xing vs. Pan Yang, 2009-05-14
Chen Yaoye vs. Gu Li, 2013-11-02

triple ko sgf triple ko sgf triple ko sgf

On the left Black has to capture a ko, for otherwise White fills at A1 and Black loses. Neither player can escape from the cycle. In the middle Black must not have time to fill at F8, so White captures at A15. On the right Black has no choice but White could fill at T5 and start a real ko. It is good for him since Black needs three approach moves (N5, O4, J1) so Black has to ignore three White threats.

Two groups with two common kos and one further ko

He Xin vs. Zhang Chao, 2008-07-17

triple ko players sgf

It is White's turn. If White wants, he can keep capturing one of the three kos adjacent to the black group, and Black, being reduced to a single liberty, is forced to reply and capture another one of these three kos. On the other hand, White can play elsewhere. Black cannot fill a ko. Black can take a ko, and then White replies by taking the other, and then Black has to play elsewhere as well. So it is White's choice: a Void game because of a cycle in the triple ko, or a continuation. If White chooses the continuation, then details of what happens afterwards depend on the rules for the end of the game. White will have the disadvantage of not being able to win any kofight since Black has an unending supply of threats.

Kaji Kazutame vs. Watanabe Hideo, 1953-08

triple ko sgf

It is Black's turn. If he captures at A10, White is forced to capture at C7 and then Black is forced to capture at A8. If now White takes a Black liberty with G8, then Black C8, White A11, Black B9 and White loses. So, G8 is no good, and White has to play A11, Black C8, White A7 and the cycle repeats. The same cycle occurs if Black starts at A8 instead of A10.

Another example:

Kim Yoonyoung vs. Yoshida Mika, 2010-11-23

triple ko sgf

It is White's turn. Again a cycle is forced.

And another:

Another - it might be called a quadruple ko, but the result was given as "Void, due to triple ko":

Liu Jianchang vs. Chen Qingyu, 2012-04-16

triple ko sgf

White can play elsewhere and allow Black to fill the ko at L19 or P15. Afterwards it is a triple ko, and a cycle is forced.

Yet another:

anon. vs. anon., 2006-10-20

triple ko sgf

Two 1-eye groups with two common kos and one further ko

Lee Wondo vs. Lin Shuyang, 2010-08-05

triple ko photograph sgf

It is Black's turn. If Black keeps playing the three kos in turn, White has no chance to connect a ko, and we cycle. Black can choose to deviate by capturing at T19, getting himself an additional liberty. But White has one eye and three false eyes, and Black needs to fill two of these false eyes, and would die himself. So, neither player has a choice here.

Double-ko seki and one additional ko

A double-ko seki in the top left corner provides an unlimited supply of ko threats for the ko in the bottom right. (Contributed by macelee.)

Park Taehee vs. Kim Dayoung, 2017-03-07

triple ko sgf

Need to win a ko fight

When players think the game is close they may use sources of infinite ko threats to fight a single ko for one or two points. For example, in

Cho Chikun vs. O Rissei, 1998-10-15

triple ko sgf

the players cycled through the three kos at A10, C10, and L17. The aim was to win the unimportant ko at L17. Threats at A10 and C10 suffice: both players threaten to continue to the next ko, with higher stakes. This infinite source of ko threats means that neither player needs to give up the ko at L17.

Another example:

Kim Hyeongwoo vs. Heo Yeongho, 2009-11-23

triple ko sgf

The last move was a White capture at O7. The game is close. White could have made two eyes with T7, but could perhaps not afford a Black capture at P9, and prefers a Void result.

Another example:

So Yokoku vs. Zhu Songli, 2006-04-17

triple ko sgf

Here the players fight a ko at Q13, and find infinitely many ko threats at A12 and C12. A mistake? Black is ahead, so White is interested in a Void result. The Black group around M9 has no eyes and needs a connection to the outside world. It is Black's turn. I think S14 suffices. Then White needs to prevent the loss of four stones at K18, and Black plays at R12 and P15 and wins.

Filling a ko

It is dangerous to fill a ko in a triple-ko situation, and one has to count carefully. For example, this amateur game ended in No Result, because of triple ko. White could have captured the large black group by filling the ko, but would then have been unable to reply to a Black threat e.g. at M1, and Black would have won.

triple ko triple ko sgf

Similarly, in

Yamashita Keigo vs. Kono Rin, 2013-09-27

triple ko sgf

white can fill a ko and turn the triple ko into an ordinary ko. However, black would win since he has the threat at A.

Unfavorable ko

In the situation

O Rissei vs. Mimura Tomoyasu, 2003-03-23

mistake to fill ko sgf

Black (O Rissei) played T11 instead of T16, turning the triple ko into an ordinary ko that is very favorable for White. Black would have to find two threats that White reacts to, and ignore three White ko threats. Quickly afterwards he resigned.


On the other hand, in the situation

Choi Cheolhan vs. Luo Xihe, 2005-12-16

ok to fill ko sgf

White (Luo Xihe) filled at K14, turning the triple ko into an ordinary ko that provided him with a single threat that had to be ignored by Black. His threat P10 was sufficiently large, and he won by 7.5 points in spite of the loss of the big white group.


In the game below Black and White found themselves in a triple ko cycle, and by mistake Black took the wrong ko. According to the rules that illegal move was considered a pass. Now White filled the ko at L7 and Black had to resign. (Corrected story due to macelee.)

Wang Lei vs. Zhou Heyang, 2001-04-23

black passes sgf

Long ko-fight

In the situation below, White decided to break the triple-ko cycle and filled at Q19. That gave Black the opportunity to capture first. After some 150 more moves, White lost.

Cho U vs. Gu Li, 2006-05-01

white fills sgf

Quintuple ko

In the situation below we have a triple ko in the upper right, and furthermore two kos at M8 and O1. After spending 18 moves in this quintuple ko cycle, Black decided to break out, capture at N3, and let White have the upper right hand corner. This worked out well, and he won by 9.5 points.

Yang Hui vs. Chen Linxin, 1992-07-04

quintuple ko sgf