EVENT
BOARDSIZE 19
SETUP W C17 D16 F17 C12 C8 C6 D4 E3 R17 Q17 O17 O18 L4 M4 N4 O3 
SETUP B B16 C14 E14 D11 C10 E8 M17 N15 P16 Q16 R16 Q10 Q4 Q6 N5 M5 K6 
MARK 5@K6 4@M4 3@M5 2@N4 1@N5
COM
Problem 169. White to play.  

Black maps out a huge moyo with the moves to 5. The way you counter
it must be considered carefully. Do you go in lightly or with
a bang ? 
ENDCOM
W 1 R8
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Jumping in with White 1 was chosen because there was every expectation
that White could live on the right side by playing this move.
ENDCOM
  VAR
  W 1 R5
  USER
  CORRECT ANSWER
  ENDUSER
  COM
  Correct Answer.

  It is also possible to play 1 here, and it would not be easy
  to kill this stone.
  <=
  ENDCOM
  ENDVAR
  VAR
  W 1 L10
  COM
  Failure.

  If White wanted to make an erasing move, White 1 would be a good
  guess.
  ENDCOM
  B 2 N10
  COM
  Black would respond by playing 2 and White's stone seems to be
  a little out of focus. It is always a perplexing problem to
  decide whether to erase or invade. You have to consider the distribution
  of stones, which stones are weak, the scale of the moyo, etc.,
  in making your decision.
  <=
  ENDCOM
  ENDVAR
B 2 Q8
COM
If Black attaches with 2, ...
ENDCOM
  VAR
  B 2 R10
  MARK 1@R8
  COM
  Variation.

  If Black defends with 2, White will look on 1 as a probe ...
  ENDCOM
  W 3 M9
  COM
  ... and play 3.
  <=
  ENDCOM
  ENDVAR
  VAR
  B 2 R9
  COM
  The actual game.

  In the actual game, Black attacked with 2.
  ENDCOM
  W 3 P9
  COM
  White 3, escaping lightly, is a skilful move.
  ENDCOM
  B 4 O5
  W 5 Q7
  MARK 1@R8
  COM
  The stones at 1 and 5 will probably sacrificed.
  ENDCOM
  B 6 R6
  W 7 P10
  B 8 P11
  W 9 O11
  B 10 Q9
  W 11 O12
  B 12 Q12
  W 13 P14
  B 14 R14
  W 15 L12
  MARK 5@Q7 1@R8
  COM
  They should be considered as decoys while White goes about the
  main business of erasing Black's moyo with the moves up to 15.
  <=
  ENDCOM
  ENDVAR
W 3 R9
B 4 Q9
W 5 S6
B 6 R10
W 7 R5
B 8 Q5
W 9 R3
COM
... up to White 9, Black gets a strong wall on the outside. But
White is not dissatisfied with the territory she has gotten on
the right. What is worrisome is the blackness that pervades the
center of the board. White has two ways into the center.
ENDCOM
B 10 G16
COM
Black blocks one of then by pressing with 10 ...
ENDCOM
W 11 G17
B 12 H16
COM
... and 12.
ENDCOM
W 13 J7
COM
However, White can still come in with 13, so she is satisfied.
<=
ENDCOM