EVENT
BOARDSIZE 19
SETUP W O17 O16 N14 M14 C14 D10 C6 R6 S4 
SETUP B D16 F16 K16 Q16 P17 Q14 O14 N13 D4 F4 Q4 O3 
COM
Problem 37. Black to play.  

White's stones at the top are heavy. How should Black attack
them ? 
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B 1 M16
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black 1, threatening to separate the white stones, is the vital
point of this position.
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  VAR
  B 1 O15
  COM
  Failure.

  Black 1 is not a good move.
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  W 2 M16
  COM
  It provokes White to play on the vital point of 2. White's stones
  now have more stability.
  <=
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  ENDVAR
  VAR
  B 1 M13
  COM
  Failure.

  Pushing along the top with 1 ...
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  W 2 L14
  B 3 L13
  COM
  ... and 3. just makes White strong.
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  W 4 K14
  MARK A@H16
  COM
  Black is now vulnerable at the point A.
  <=
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  ENDVAR
W 2 O15
COM
If White plays 2, ...
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  VAR
  W 2 N15
  COM
  Variation.

  White could draw back to 2.
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  B 3 O13
  MARK C@R8 A@R17 B@H16
  COM
  Again, Black connects at 3. White would like to play A or B,
  but if she does, her stones at the top could get into trouble.
  On the other hand, Black is free to attack the white stones in
  the lower right with a pincer at C.
  <=
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  ENDVAR
B 3 O13
COM
... Black will connect at 3.
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W 4 M15
COM
White must defend against the cut with 4 and ...
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B 5 K14
MARK \t@M16
COM
... Black continues the attack with 4. The marked black stone
is on the vital point, depriving White of eye shape.
<=
ENDCOM