EVENT
BOARDSIZE 19
SETUP W D16 C4 M3 R5 
SETUP B E3 Q3 Q5 Q8 Q16 
COM
Problem 153. White to play.  

Black has just attached against the white stone on the lower
right side. How should White respond ? 
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W 1 J3
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

White should extend to 1. This move is both an extension and
a pincer.
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  VAR
  W 1 R4
  COM
  Failure.

  It is not a good idea for White to try to live in the corner.
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  B 2 Q4
  W 3 R3
  B 4 R6
  W 5 S6
  B 6 S7
  W 7 R7
  B 8 Q6
  COM
  Black builds a thick wall with the sequence to 8 and, ...
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  W 9 S8
  COM
  ... after White 9, ...
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  B 10 J3
  COM
  ... Black pincers with 10, making a moyo at the bottom.
  <=
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  ENDVAR
B 2 R4
COM
If Black secures the corner with 2, ...
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W 3 D3
COM
... White goes on the attack with 3 ...
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B 4 E4
W 5 D6
COM
... and 5.
<=
ENDCOM