EVENT
BOARDSIZE 19
SETUP W D16 F16 J17 D4 L3 O3 Q2 N16 O17 P17 P14 O13 Q13 R14 
SETUP B C14 C11 R3 Q4 Q6 R10 Q10 Q16 Q17 Q15 O16 O15 Q14 
MARK \t@O13 \t@P14 \t@Q13 \t@R14
COM
Problem 34. Black to play.  

How should Black attack the marked white stones ? 
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B 1 P12
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black first peeps with 1, ...
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W 2 P13
B 3 M16
COM
... then attacks the three white stones at the top with the clamp
of 3.
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  VAR
  B 3 N14
  COM
  Failure.

  Black 3 aims at both the white stones at the top and on the right,
  but it lacks in severity.
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  W 4 O12
  B 5 O10
  W 6 M12
  B 7 N17
  COM
  When Black cuts at 7, ...
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  W 8 N18
  COM
  ... White can live at the top with 8 ...
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  B 9 M17
  W 10 M18
  COM
  ... and 10. White's stones are now safe.
  <=
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  ENDVAR
W 4 N15
COM
If White extends to 4, ...
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  VAR
  W 4 M17
  MARK \t@M16
  COM
  Variation.

  If White answers the marked stone with 4, ... 
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  B 5 N15
  COM
  ... Black presses along the top with 6 ...
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  W 6 N17
  B 7 L16
  COM
  ... and 8.
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  W 8 L17
  B 9 N12
  COM
  He then casts a net with 9, trapping the white stones.
  <=
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  ENDVAR
B 5 N17
COM
... Black cuts at 5. If White ...
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W 6 M17
B 7 N18
W 8 M18
B 9 N14
W 10 M15
B 11 M14
W 12 L15
COM
... insists on saving her stones at the top with the sequence
to 12, 
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B 13 N12
COM
... Black casts a net with 13, ...
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W 14 N13
B 15 M13
W 16 O12
B 17 O11
COM
... trapping the white stones on the right.
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W 18 P11
COM
If White cuts at 18, ...
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B 19 O10
COM
... Black extends at 19 and White's stones can't get two eyes.
<=
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