EVENT
BOARDSIZE 19
SETUP W E16 F17 G16 L17 D4 M4 N3 N5 Q6 R9 Q4 R4 R5 S4 S3 
SETUP B C16 E17 D17 C14 F3 K3 Q5 P5 P4 P3 R3 R2 S2 P17 R16 
COM
Problem 169. Black to play.  

In this position it is urgent for Black to settle his stones
in the lower right. Where should he play ? 
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B 1 O2
MARK B@T2 A@M2
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black should defend his stones with 1. Black doesn't have to
worry about their safety anymore because he can either link up
his stones on the left with A or make two eyes with B.
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  VAR
  B 1 P6
  COM
  Failure.

  It might seem more natural for Black to prevent the blockade
  and advance into the center with 1 ...
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  W 2 Q7
  B 3 P7
  COM
  ... and 3, but ...
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  W 4 Q3
  COM
  ... White could force with 4 ...
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  B 5 Q2
  W 6 O2
  COM
  ... and 6.
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  B 7 P2
  W 8 N7
  COM
  Black's group doesn't have two eyes and White goes on the attack
  with 8.
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  B 9 P8
  COM
  If Black 9 next, ...
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  W 10 Q10
  COM
  ... White will play at 10.
  <=
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  ENDVAR
W 2 P6
COM
If White blocks with 2, ...
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B 3 C6
MARK A@O6
COM
... Black is happy just to play the approach move of 3. Black
is threatening to hane at A, so White cannot avoid a disadvantageous
fight.
<=
ENDCOM