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 Post subject: 1928 dispute about ten thousand year ko
Post #1 Posted: Wed Feb 21, 2024 2:12 am 
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In 1928 there was a dispute about the following position arising in a game between Segoe Kensaku and Takahashi Shigeyuki. It was claimed that the game can not end since white can't fill the ko in the ten thousand year shape :scratch: The dispute was resolved in the end when it was decided that white won and black didn't lose.

Click Here To Show Diagram Code
[go]$$W
$$ ---------------------------------------
$$ | . . . O O O . . . O . O O O O X . . . |
$$ | . O O . . O X . . . O . O X X X . . . |
$$ | . X X O O X . O O O . O X . . . . . . |
$$ | . X . X O O . . . O O X X X . X . X . |
$$ | . X X . O O X X X O O X . . X . . . . |
$$ | . O . X . O X O O O X X . X O . O X . |
$$ | O O O X X X O O O X X O X X O . . X . |
$$ | . O X O X O . . O X X O X X . O O X . |
$$ | . . . O O O O . O O O O O X X O X X X |
$$ | . O O O X X X O O O O X O X O X X O O |
$$ | O O X X O X O O X X O X X O O O O O . |
$$ | X O O X . X X X X O O X X X X O O X O |
$$ | X X X X X . X O O O X X X . X O X X X |
$$ | X O X X O X X X X O O X X X O O . X . |
$$ | X O O O O O X O O . O X O X X O O O O |
$$ | X O O X O X X X O , O O O X O X X X X |
$$ | X X X X O O O O O O . . O X . X . . . |
$$ | . . X X X X O . . . O O X X X . . . . |
$$ | . X . O . X O . . . . O O X . . . . . |
$$ ---------------------------------------[/go]


This occurred to me when I was watching a game between Sada Atsushi and Okawa Takuya in the Kansai Kiin 1st place tournament. The game ended in the following position. Notice how black will never be able to connect the ko. It is claimed that Okawa Takuya, who was black, resigned in this position and the game did end. Probably not a strategic mistake, he appears to have been behind. The similarity with the shape of 1928 is striking.

Such shapes probably aren't that rare or are they? Possibly there is some element of trying to make a beautiful kifu when resigning. Certainly it is interesting to think about how this position would have been resolved. It is too bad that the game ended here.

Click Here To Show Diagram Code
[go]$$B black 7, white 2 prisoners
$$ +--------------------------------------+
$$ | . . X . . . . . . . . . . . O O X . X|
$$ | . X X X . . X X X X . . X O O X X X O|
$$ | X O X O . X . . X O X X . O X X . O O|
$$ | . O X O X X . X O O O O O O O , X . .|
$$ | . O X O X O X X O X X . O X X X X X X|
$$ | . X O X X O O X X X . X O O X X O O O|
$$ | . O O O O X O O O O O O O O X O O O X|
$$ | . . . . X X O . . . X . O X X O . X .|
$$ | . O X X . . X O O . . X O O O O O . X|
$$ | . . O , . . X X O , X O O . X X O . X|
$$ | . O O X . X . X X X X X O . X O . O X|
$$ | . O X . X O X O O O O X O X X O O O X|
$$ | . X X . X O X O . X O . X . X O . O X|
$$ | . . . X O O . O . X . X X X X X O . X|
$$ | . . X X O . . O X . X X O . . O O . .|
$$ | X X X O O X . X O X . X O X X X O O X|
$$ | X O O . O . X O O X O O O O O X X X .|
$$ | O . O . . O O O X O O . X O . O X . .|
$$ | . O . . . . . . . . . . . . O . . . .|
$$ +--------------------------------------+[/go]

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 Post subject: Re: 1928 dispute about ten thousand year ko
Post #2 Posted: Wed Feb 21, 2024 2:18 am 
Judan

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Almost all 10,000-year kos (or potentials for their occurrences) are dissolved before the game end. Rules fun starts if they survive until the game end / stop.

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 Post subject: Re: 1928 dispute about ten thousand year ko
Post #3 Posted: Wed Feb 21, 2024 2:50 am 
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Probably this one wouldn't have any chance of surviving until counting. It would have to be white who thought he could claim the game didn't end, or his team mate as in the 1928 game, but white is leading anyway if it is seki.

It is confusing me that there are approach moves. It is basically the usual ten thousand year ko but with more approach moves. The approach moves aren't that meaningful for the ko situation, black can't anyway end the ko. I guess I posted in the wrong subforum, it is not much about rules.

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 Post subject: Re: 1928 dispute about ten thousand year ko
Post #4 Posted: Wed Feb 21, 2024 3:21 am 
Oza

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Why is there any doubt about how this KK game would have been resolved? Yes, it's an interesting position and yes, the Japanese rules are far from ideally comprehensive (e.g. the official rules example does not show the case where the 1-1 stone remains uncaptured), but a rule now exists. It is seki.

The 1928 dispute was at a time when no rule existed but, even so, was probably more about personal animosities and promotion points than about the logic of rules. (See my biography of Segoe for details.)

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 Post subject: Re: 1928 dispute about ten thousand year ko
Post #5 Posted: Wed Feb 21, 2024 9:59 am 
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It is an interesting position. Black could have had seki but he went for this ko. He also played a move just before that should be smaller than defending this corner. It would appear that leaving a ten thousand year ko could be perceived as a closer game. That made me think of when it was claimed that the game couldn't end.

Certainly they would know what to do. For example if there were no moves left on the board and the ko was left to connect, except it is black to move. They would know what to do :) I think it would parallel what happened when Iyama and Ichiriki ran out of stones. They knew exactly what to when that happened.

This concept that different ways of losing or winning don't come with the same value exists in many games. Many Go players, for example, don't value much winning on time. Chess players seem to be so embarrassed by being checkmated that it is customary to resign when it is inevitable. I'd think this consideration also played a role in the 1928 game. They didn't want to lose and found it to be a better way of losing to claim the game couldn't end. Having a dispute probably has little value for most players when they are losing but it happens. The idea that the ko isn't finished and therefore the game isn't over is an interesting, if impractical, idea.

In last night's game fighting the ko as black would be impossible but creating it showed spirit. The printed kifu will also be more interesting to look at and this was an interesting game. If you look closely you can see that white has a 60+ stone group that only has two sure eyes. Maybe it will be more rewarding for many to play through it because it ends with a bang.

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