Cho Chikun defends Kisei titleOn March 11, Cho Chikun beat
Koichi Kobayashi in the sixth game of the best-of-seven Kisei title
match to win this title for the fourth consecutive time and eight
times altogether. Through his victory in this most prestigious of
title matches, Cho left no doubt in anyone's mind that he is Japan's
strongest player.
The match started out with Cho winning the first two games.
Kobayashi won the third, but Cho won the fourth. Therefore,
Kobayashi had to win the next three games to take the title.
Kobayashi won the fifth game, and, in the sixth, he had a good
position after Cho made a strategic mistake in the transition from
the opening to the middle game.
But Cho fought back by invading the huge territory that Kobayashi
had mapped out. Cho's invading group, surrounded on all sides by
Kobayashi's stones, had to either make two eyes to live or link up
to one of its allied groups. After a series of subtle moves by both
players, Cho skillfully linked up his endangered group to one of his
secure groups, then went on to eke out a 5.5-point win.
Figure 1 shows the
position after 127 moves. Kobayashi has just played the marked black
stone, and the marked white ones are in danger of being captured.
After a series of subtle moves, Cho managed to link them up to his
secure group of stones in the bottom righthand corner.
In spite of this setback, Kobayashi is clearly at the height of
his go strength. At the end of last year, he won the Tengen title,
on March 6 he won NEC Cup and he is challenging Naoto Hikosaka for
the Judan title. (Kobayashi won the first game of this best-of-five
match.)
Cho on the other hand appears unbeatable. Besides the Kisei
title, he holds the other two top titles--Meijin and Honinbo--making
him a "triple-crown champion" of Japanese go, a position he has held
for the last three years. In May, he will defend his Honinbo title
for the 10th straight time, but no potential challenger from the
league is likely to give Cho much trouble.
If you are interested in seeing the Kisei title match games, they
are posted on Yomiuri's Web site at:
http://www.yomiuri.co.jp/index-e.htm. Scroll to features and click
"Kisei Title
Match."
Answer to last week's problem
In Problem
11, you were asked to capture the two marked white stones. The
correct answer is for Black to cast a net with Black 1. If White
tries to break out with 2, Black blocks with 3, and White has no way
to break out into the open. If he plays 4 (or A), Black 5 (or B)
puts the white stones in atari. Black cannot capture the white
stones with a ladder. It is wrong to play the sequence to 5 in the
next diagram, because of the marked white stone. White 6 threatens
to capture Black 3. If Black plays 7, White captures a stone with 8
and Black's position collapses. In previous columns, we studied
various capture techniques. First of all, I would like to review the
rules of go that we have introduced so far.
Rule 1. The board is empty at the start of the game.
Rule 2. Black makes the first move, after which he and
White alternate.
Rule 3. A move consists of placing a stone of one's own
color on an empty intersection.
Rule 4. A stone or a solidly connected group of stones of
one color is captured and removed from the board when all the
intersections directly adjacent to it are occupied by the enemy.
Illegal movesA corollary of the last rule is that you are
not allowed to place a stone on an intersection that is not
connected to an empty adjacent intersection. In other words, you are
not allowed to commit suicide.
For
example, Black cannot place a stone at 1 in Diagram 1 or
2. In Diagram 1, the adjacent intersections are occupied by the
marked white stones and Black 1 would be completely surrounded.
Black 1 in Diagram 2 is also an illegal move because this
stone's adjacent intersections are occupied by the marked white
stones.
White is not allowed to play 1 in Diagram 3 either. This
move would result in a three-stone white group without any
liberties.
When capturing stones, however, you are allowed to play such
moves. For example, if Black has played the marked stone in
Diagram 4, then Black can play 1 because this move eliminates
the liberties of the five white stones. The result of this capture
is shown in Diagram 5. Likewise, if Black has already played
the marked stone in Diagram 6, he can play at 1 and capture
the two marked white stones.
Living groupsWe are now going to show you a group that can
never be captured. The white group in Diagram 7 is completely
surrounded by black stones, but it cannot be captured. The reason is
that it has two internal points at A and B (Diagram 8) called
eyes. Black cannot play on either of these two points because it
would be an illegal move. Therefore, the white group can never be
captured since the points A and B leave this group with two
liberties. The points A and B are called "eyes." From this, we can
define a living group: a group is alive if it can form two eyes.
Look at the white group in Diagram 9. It may seem as if
this group has two eyes, but this is not the case. It has only one
eye and this is called a two-point eye space. Black can kill the
white stones by playing at 1 in Diagram 10. If White captures
this stone with 2 in Diagram 11, White is left with only one
eye and Black can play at 3 in Diagram 12 and capture the
five white stones.
Problem 12.
White to play and make two eyes. If it were Black's move, where
would he play to capture the white stones?
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