EVENT
BOARDSIZE 19
SETUP W Q3 C16 D16 D17 D15 G17 H17 J17 F12 C12 D12 E11 E10 C10 
SETUP B Q16 D4 J16 H16 K16 E15 F15 C15 C13 D13 D14 E13 E12 F11 G11 
MARK A@L17 B@R10 C@R5 D@F3
COM
Problem 148. White to play.  

Black has a thick position in the upper left, but in compensation
White has made profit at the top. White has sente and would like
to use it to get the most out of this position. Where should
she play ? 
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W 1 R5
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

White goes for territory by making a corner enclosure with 1.
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  VAR
  W 1 L17
  COM
  Failure.

  White 1 is a big move, ...
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  B 2 Q5
  COM
  ... but Black will approach at 2.
  <=
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  ENDVAR
  VAR
  W 1 R10
  COM
  Failure.

  If White 1 here, ...
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  B 2 Q5
  COM
  ... Black will again play 2. White's stones will then be scattered
  and lack unity, so Black would now be able to utilise his thickness
  by attacking them.
  <=
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  ENDVAR
B 2 K17
COM
If Black turns at 2, ...
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  VAR
  B 2 Q10
  COM
  If Black 2 here, ...
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  W 3 L17
  COM
  ... White will jump to 3.
  <=
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  ENDVAR
W 3 R17
COM
... White invades the corner with 2.
<=
ENDCOM