EVENT
BOARDSIZE 19
SETUP W D16 F17 L17 M16 O17 Q18 K8 J5 L5 D4 E3 F2 C6 D11 Q7 R4 
SETUP B Q16 R17 Q14 M14 K15 Q9 M8 L3 J4 H4 F4 F3 G2 P4 Q3 R3 
MARK \t@Q7 \t@R4
COM
Problem 52. Black to play.  

The two marked stones are not very strong, but they still have
some aji. How should Black attack them ? 
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B 1 R9
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black 1 forces the white stones to escape ...
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  VAR
  B 1 O8
  COM
  Failure.

  Black 1 looks like a strong move, which builds a moyo in the
  center, but ...
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  W 2 R9
  COM
  ... this gives White the chance to attach with 2.
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  B 3 R10
  COM
  If Black 3, ...
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  W 4 S10
  COM
  ... White hanes with 4 and she will easily be able to make sabaki.
  <=
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  ENDVAR
W 2 O7
COM
... with 2, but ...
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B 3 M6
COM
... Black prevents them from linking up with 3 ...
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W 4 O5
B 5 M5
COM
... and 5.
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W 6 P5
COM
 White tries to make shape with 6, but ...
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B 7 R6
COM
... Black 7 leaves White's stones eyeless within Black's sphere
of influence.
<=
ENDCOM