EVENT
BOARDSIZE 19
SETUP W C12 K17 K15 M17 Q17 R17 R18 S16 S15 R15 R14 
SETUP B D17 C14 H17 O17 Q18 S17 Q15 Q16 R16 O15 
MARK 2@S15 1@S17
COM
Problem 106. Black to play.  

White answers the cut of Black 1 with 2. What should Black do
now ? 
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B 1 S18
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black should play 1.
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  VAR
  B 1 P17
  COM
  Failure.

  Black 1 also makes shape, ...
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  W 2 S18
  COM
  ... but after White 2, there is no play left for Black in the
  corner. See the next problem for amplification.
  <=
  ENDCOM
  ENDVAR
W 2 P18
COM
White has no choice but to atari with 2.
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  VAR
  W 2 P17
  COM
  If White plays 2 here, ...
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  B 3 P18
  COM
  ... Black plays 3 and the white stones will be captured.
  <=
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  ENDVAR
B 3 P17
COM
Now Black can make good shape by playing atari with 3.
<=
ENDCOM