EVENT
BOARDSIZE 19
SETUP W C16 D17 G17 D11 F11 Q3 N3 Q9 
SETUP B C15 F15 D7 D4 R5 O5 Q16 Q13 
MARK \t@C16
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Problem 66. Black to play.  

White has attached with the marked stone, hoping to put the two
black stones under siege. How should Black counterattack ? 
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B 1 E16
USER
CORRECT ANSWER
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Correct Answer.

Black should play the forcing moves of 1 ...
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  VAR
  B 1 D15
  COM
  Failure.

  Answering the attachment of the marked stone by standing at 1
  here leaves the black stones heavy.
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  W 2 E16
  COM
  White peeps with 2 and ...
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  B 3 E15
  W 4 H16
  B 5 H13
  W 6 H11
  B 7 H15
  W 8 K16
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  ... the black stones are under attack after White 8.
  <=
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  ENDVAR
W 2 E17
B 3 B16
W 4 B17
B 5 H15
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... to 5.
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W 6 J16
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After White 6, ...
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B 7 H11
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... Black caps with 7 and the two white stones on the left side
are under attack.
<=
ENDCOM