Videos Lectures Games commentary Wu's games Outside content

Possible continuation of the ko rule dispute

There have been many interesting discussions in rec.games.go on the rules. Here is a famous historical example.

Takagawa played seven 3-game series with Go Seigen from 1952 to 1961. The 2nd game of the 5th 3-game series (played in January of 1959) produced a problem concerning the go rules (Japanese rules), and it became a hot topic at that time. This problem was still not completely solved when the book in which I read the story was published in 1987. (The current Japanese rules were revised on April 10, 1989 and effective from May 15, 1989.)

The following is the game at W #244 (F16) — the last move recorded. If counted as is now, W has 55 points, B has 59 points, or a 4-point lead by B on the board. Subtract that from the 4.5-point komi, it should be a 0.5-point win in favor of W.

 

 

However, B had moves remained at the center. That is, If B[a] (M10) cut, B could force a ko (O10-O11). So if W wanted to prevent such a ko, he would have to add one more move there (inside his territory) — then it would be a 0.5-point win for B instead. Therefore, W (Go Seigen) decided not to add this move.

Mainichi Shimbun’s reporter started an article on the game as the
following:

The 2nd game of Takagawa Honinbo vs. Go Seigen 9-dan’s 3-game series ended on #244 at 10:10 in the evening on the 2nd day (10th). But at this moment, a problem of whether or not an addition of a move was necessary arose. Therefore, to be precise, this game was only close to the end.

Honinbo thought Wu 9-dan should add a move, but Wu 9-dan believed it was not necessary. In the game (near the end), Go Seigen actually prepared this problem by making a ko threat at lower right bigger, and at the end, he said, if there was any problem, they should play it out. Takagawa, however, had counted that Wu would certainly add a move, because according to Nihon Ki-in rules at that time, this move should be added.

Both Wu and Takagawa had smiles on their faces while insisting their own viewpoints, and the atmosphere beside the board was relaxed. Not until the news was about to go public, referee Hasegawa Akira 7-dan made the final decision: “The game ends after W adds one more move.” That is: Takagawa (B) wins by half point.

Referee in chief Hasegawa Akira 7-dan’s “B wins by half point” decision was based on the Nihon Ki-in’s go rules written on October 2, 1949. At that time, in treating a possible ko like this at the end of a game, it was rigidly stated that W (in this case) had to add a move to
eliminate this ko. I roughly studied the 1989 version of Japanese rules,and it seems to me that the new version has shifted in favor of “playing out.” (But I am not an expert on rules. )

What if Wu-Takagawa game was played out regarding to that possible ko?
The book I read had some clear commentary on it. I have compiled it to a game record (mgt) and it’s saved in a separate file story.takagawa.a”. (No commentary on the actually played moves, though ) The playing out isquite interesting, consisting the consideration of passes.

After this Wu-Takagawa encounter, Nihon Ki-in admitted that there werestill some regretable spots in the rules, and it was promised to be
improved. Wu also clearly stated, before the improved version came out, he would obey Nihon Ki-in’s go rules when he played with Nihon Ki-in bounded players (Go Seigen was not a member of Nihon Ki-in then). The problem was temporarily solved, but after 1/4 of a century (the game was played in 1959), this particular part of the rules was still not improved (I am not sure if the 1989 version did a particular improvement with respect to this problem).

Leave a Reply

%d bloggers like this: