Meijin title matchOn Nov. 12, Cho Chikun defended his
Meijin title by winning the seventh game and defeating O Rissei 4-2
in the best-of-seven match with one game ending without result. With
this victory, Cho has maintained his dominance over the three top
Japanese go titles: Kisei, Meijin and Honinbo.
O Rissei is one of the top players in Japan. He has had
especially good results this year. In March, he won the LG Cup, a
major international tournament sponsored by the South Korean LG
Group. Then, in May and June, he challenged Cho for the Honinbo
title (he lost 4-2). In August he swept the Meijin league with eight
straight wins to become the Meijin challenger. He is also the
challenger for the Oza title, one of the big seven open titles.
O was born in Taiwan in 1958 and, like Cho, came to Japan to
pursue a career as a professional go player. He became a
professional at the age of 14 and attained the highest rank of 9-dan
in 1988. Over the years, he has won numerous titles, but it is only
in the last three years or so that he has come into his own. His go
is much admired by his fellow professionals, and he has created many
new moves in the opening.
Both Cho and O play tight territorial games as opposed to an
influence-oriented strategy. But, in their games with each other,
Cho seems to be able to force O to play for influence, which goes
against his nature. This is one of the hallmarks of Cho's strength:
he does not let his opponents play the way they want.
The title match this year was especially noteworthy because the
fourth game ended with a no-result, the first time this has happened
in a major title match. This requires an explanation.
Draws never occur in tournament games because of the "komi"
system, which evens up the contest. Since it is estimated that
making the first move is worth about five to six points, the player
with Black (who makes the first move) gives the player with White 5
1/2 points.
At the end of the game, these extra points are added to White's
territory. Therefore, after the game is counted, one side will have
at least half a point more than the other side. The only way that a
result other than victory or defeat can occur is if some sort of
impasse develops in the game.
One of the official rules of the Japan Go Association states that
if the same whole-board position is repeated during a game, and the
players refuse to stop this repetition, the game ends without
result.
Here is what happened in the fourth game. Early in the game, one
of O's groups got into trouble, but it succeeded in living because,
if Cho attacked it, it could live by creating a double ko. However,
another ko developed in another part of the board later in the game.
Cho felt that he might lose by half a point, so he attacked O's
group and O had to defend by turning the position into a double ko.
There were now three active kos on the board. If either side lost
one of these kos, he would lose the game. Thus, neither side could
yield, and, eventually, the whole-board position repeated itself, so
the game was declared no-result.
It is extremely rare for a game to end with no result, but,
interestingly, this was the fourth time in Cho's career that one of
his games ended in a no-result.
Double koLet's look at the double ko that occurred in the
fourth Cho-O game. O was White. Diagram 1 shows the position
after 98 moves. The white group in the middle of the left side is
alive. It has one eye at A and can easily get another eye at B.
If Black plays 1 in Diagram 2, White defends with 2. Black
captures the marked stone with 3, threatening to capture the stone
to the right of 1. But White captures the stone at 1 with 4. If
Black connects where the marked stone was, White will connect at 1
and he now has two eyes for his group at A and B (see Diagram
1)
Suppose Black tries to fight the ko around 1 by making a threat
elsewhere. If White answers this threat, Black can come back and
capture the stone at 4, but White will play the other ko by
capturing the stone at 3.
As you can see there are two kos here, and, for Black to kill the
white group, he has to win both kos--the one around 1 and the one
around 3. But this is impossible, so the white group is
unconditionally alive.
However, when a third ko occurred later in the game, the
stability of this position was upset. In our next installment, we
will show the final position that led to the no-result.
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