EVENT
BOARDSIZE 19
SETUP W D17 C15 D4 P4 K3 M3 N3 O3 O18 P18 Q17 R17 S17 S16 
SETUP B R4 P3 Q3 O4 O5 M4 Q10 K16 N17 O17 P17 Q16 R16 S15 R14 
MARK 12@R14 11@S17 10@S15 9@S16 8@N17 6@O17 7@O18 5@P18 4@P17 3@Q17
MARK 2@R16 1@R17
COM
Problem 167. White to play.  

White has taken the territory in the upper right corner, completing
her profit-oriented strategy. But she must now cut Black's moyo
down to size. To find the right move, you need to rely intuition
rather than analysis.  
ENDCOM
W 1 M9
MARK \t@P4 \t@N7 \t@M10 \t@L13 \t@O5 \t@K16
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Before discussing the solution, we will show you how to determine
the limits of your invasion. We have marked the line stretching
from the outermost black stones (marked) enveloping his moyo.
If your move is outside this line, you should have no problems,
but it might be not enough to win. If it's inside this line,
your stone could end up being captured. You have to find the
'golden mean'.

It is best to approach outside the line, your answer should be
to play 1 towards the bottom. Why ? Compare the top and bottom
parts of this moyo. On the lower right, White has a marked stone
in place. Another stone played in this area could bring the aji
of this stone to life. Therefore, it will be easier to make sabaki
in this area.
ENDCOM
  VAR
  W 1 L9
  MARK \t@N7 \t@M10 \t@L13
  COM
  Failure.

  The erasure of White 1 is too shallow.
  ENDCOM
  B 2 N9
  MARK 1@L9
  COM
  Black 2 hits just the right balance in expanding his moyo. Any
  wider and Black would be overextended. White 1 cannot be considered
  a good erasure
  <=
  ENDCOM
  ENDVAR
  VAR
  W 1 N9
  MARK \t@N7 \t@M10 \t@L13
  COM
  Failure.

  In contrast, White 1 is too deep.
  ENDCOM
  B 2 L9
  COM
  Black would immediately cap at 2.
  ENDCOM
  W 3 P9
  B 4 Q9
  W 5 P7
  B 6 Q8
  W 7 M7
  COM
  White's stones are not in danger of being captured, but ...
  ENDCOM
  B 8 L4
  COM
  ... after Black 8, White has also to worry about her stones at
  the bottom.
  <=
  ENDCOM
  ENDVAR
  VAR
  W 1 M10
  MARK \t@N7 \t@L13
  COM
  Failure.

  White plays 1 one line higher than the Correct Answer. This approaches
  Black's thick wall at the top, so it doesn't have a good feel
  to it.
  ENDCOM
  B 2 K10
  COM
  After Black 2, it is going to be hard for White to make sabaki.
  <=
  ENDCOM
  ENDVAR
  VAR
  W 1 M11
  MARK \t@N7 \t@M10 \t@L13
  COM
  Failure.

  Suppose White plays even one more line higher. This is clearly
  a bad move.
  ENDCOM
  B 2 K10
  COM
  After Black 2, it is going to be even harder for White to make
  sabaki. As the proverb says, 'Don't approach thickness !'
  <=
  ENDCOM
  ENDVAR
  VAR
  W 1 D9
  COM
  Failure.

  White 1 is too slow. It breaks the iron rule of not allowing
  your opponent to perfect his moyo.
  ENDCOM
  B 2 J10
  MARK \t@N7 \t@M10 \t@L13 A@K10
  COM
  Black will play 2 (or just A) and what was before only a moyo
  has almost become territory. In contrast, White 1 is not a very
  big move.
  <=
  ENDCOM
  ENDVAR
B 2 K9
COM
If Black caps with 2, ...
ENDCOM
  VAR
  B 2 O9
  COM
  If Black defends with 2, ...
  ENDCOM
  W 3 M11
  COM
  ... White jumps to 3. White's stones are working throughout the
  board and the limits of the black moyo have been defined.
  <=
  ENDCOM
  ENDVAR
W 3 P9
COM
... White plays 3 ...
ENDCOM
B 4 Q9
W 5 P8
COM
... and 5, seeking sabaki. However, all your moves should be
natural. Do not make unreasonable moves, trying to trick Black.
<=
ENDCOM