Before filling in the dame points, Ryu mumbled that the game had come to an end. This is the common practice, after which the opponent usually agrees and the dame points are filled in amicably. During this phase, when both players have declared the game finished, stones cannot be captured, even if they get into an atari.
But in this case, O Rissei claimed he had not heard Ryu's murmur, let alone agreed the game had finished. As the two played dame points in turn, Ryu noticed a spot where his stones were in atari. As he tried to play his second move in a row, O stopped him. The referee, Yoshio Ishida, was called, and, after scrutinizing a tape of the game, found O had not said anything and Ryu's murmur was incomprehensible. Consequently, he allowed O to play the next move and capture the stones in atari. A few moves later, Ryu resigned the game he should have won. It was a tragedy both for Ryu and for go fans.
In Japan, the rules for deciding the end of a game at official professional matches have always been ambiguous, and this has sometimes led to criticism. By comparison, the relevant World Amateur Go Championship rule states: "The players continue to play alternately until all the neutral points have been filled and all necessary defensive moves have been made."
Now this ambiguity has lead to problems in an important game, reversing the result, and possibly affecting who wins the series, with a winner's purse of 42 million yen at stake. It may be time to make firm rules for the end of the game.
The end of the game
Diagram 1 :
A number of interesting battles take place in this game. The komi, (compensation) Black gives White for playing the first move is 3-1/2(harf) points.
Diagram 2 :
(White 42 is played where the marked stone is)
From Black 25 on, the endgame starts, and the game ends at move 46, as there are no more points to be made according to Japanese rules. According to Japanese custom, the players agree that the game is finished.
Diagram 3 :
But has the game really ended ? For example, when Black plays at A, White has to answer at B in order not to lose points. On the other hand, White could play at C and, if Black answers at E, connect at C to make two points, one at G and one at F. But if Black answers white C at D, White must capture at E, and Black can take the ko at F. Theoretically, White can make a ko threat, but even if he does, it will be too small, and Black will capture at H and, when White finishes the ko threat, Black can next capture three stones with I.
Therefore in practice, White won't play at C. Just to be sure, Black would play at C as soon as possible, and White will answer at D. Black also eventually has to defend at E and White at F, after which Black can play at G to take the last dame point.
However, during the stage this diagram depicts, when both players agree that the game has finished, accidents are not supposedto happen and, indeed, can't happen by chance. For example, White may ignore black A and refuse to connect at B, arguing that B should be counted as a point for White. This is nonsense, but for the sake of argument, let's suppose it happens. What to do now? If there is a referee, he is called upon to force White to connect at B. But when there is no referee (or a stronger player) nearby, it isn't always easy to tell. That's when the game restarts. Black could then capture the marked stone by playing at B. This would lead to a full-fledged ko and either to Blacks marching into White's territory or White connecting at B after all.
Diagram 4 :
If both players play the dame points correctly, this will be the result. Black has 20 points + 3 prisoners (at D, E and F) = 23 points. White has 15 points + 4 prisoners (at A, B, and C two times) = 19. Including the komi, Black would win by half a point.
Diagrams 5-7 : images
(The following moves were made in ko: white 54, black 63, white 66, black 69, white 72, black 77, white 80, black 83, white 88, black 91 and white 100.) The first 200 moves of the fifth game between Ryu Shikun (Black) and O Rissei are provided for reference.
New Problems
Problem 1 :White to play first. What is the best result for both players ?
Problem 2 :
Black to play and connect his stones.
Problem 3 :
Again, Black plays first and lives with all of his stones. There are two correct solutions.
Problem 4 :
Black seems to be in trouble. Can you somehow connect his stones ?
Solution to last week's problem
Solution 1 :After Black saves his stones by connecting at 1, White clamped at 2. In the game, Black played atari with A, but he should have played at 3 immediately. White will capture a stone with 4 and 6, leaving Black free to take charge in the center. However, after the exchange 8 for 9, White can clamp to the right of 9 to start a ko. At the moment, as White has no ko threats to back up a ko fight, a move at 10 seems reasonable. Still, since a ko fight could erupt at any time, Black had better answer at 11 as soon as possible. This would give Black a reasonable game.
