EVENT
BOARDSIZE 19
SETUP W B17 C16 C15 D15 F14 E14 D10 C6 D4 Q6 R6 R9 P17 P16 P15 Q16 R15 M16 J17 
SETUP B C18 C17 D16 E17 E15 F15 G15 F3 J3 O4 Q4 R5 R11 R18 R17 S17 R16 Q17 O16 Q15 Q14 
COM
Problem 81. Black to play.  

How should Black attack the three white stones in the lower right
? 
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B 1 P9
USER
CORRECT ANSWER
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COM
Correct Answer.

The cap of Black 1 is severe.
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W 2 Q10
COM
If White tries to get out into the open with 2, ...
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  VAR
  W 2 O8
  MARK 1@P9
  COM
  Variation.

  In response to the cap of Black 1, White tries to make shape
  with 2 ...
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  B 3 Q8
  W 4 O6
  COM
  ... and 4. But, ...
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  B 5 R8
  W 6 S6
  B 7 S5
  W 8 S8
  B 9 S7
  W 10 R7
  B 11 S9
  W 12 T7
  B 13 Q9
  COM
  ... with the sequence to 13, Black secures the lower right corner
  and a large territory on the right side.
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  W 14 K4
  COM
  White tries to get some play with 14 ...
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  B 15 K3
  W 16 L4
  COM
  ... and 16, but her stones ...
  ENDCOM
  B 17 P7
  W 18 P6
  B 19 H5
  W 20 M6
  MARK C@O17 B@L17 A@L8
  COM
  ... are still insecure with only one eye even after she jumps
  to 20. Black has several options. He can immediately attack at
  A, but he might first want to invade at B or C, then, depending
  on how the game continues, attack at A.
  <=
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  ENDVAR
  VAR
  W 2 O7
  COM
  Variation.

  The knight's move of White 2 is another possible response.
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  B 3 N5
  COM
  After exchanging 3 ...
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  W 4 N8
  COM
  ... for 4, 
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  B 5 P11
  COM
  ... Black makes shape with 5.
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  W 6 P8
  MARK C@P6 B@R8 A@Q8
  COM
  White must defend against the sequence Black A - White B - Black
  C with 6, so ...
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  B 7 O9
  COM
  ... Black can further strengthen his stones with 7.
  <=
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  ENDVAR
B 3 P14
COM
... Black forces with 3, ...
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W 4 O15
B 5 O11
COM
... then blocks White's access to the center with 5. White's
stones are still insecure.
<=
ENDCOM