EVENT
BOARDSIZE 19
SETUP W C17 E3 P17 R4 Q3 O4 O7 Q8 
SETUP B C4 Q17 R16 P16 M16 P6 Q5 R5 
MARK \t@O7
COM
Problem 60. Black to play.  

White has just played the marked stone, trying to trap the three
black stones. How can Black escape and turn the tables on White,
putting her under attack instead ? 
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B 1 N5
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

The knight's move of Black 1 is the key move. It attacks White's
position at the bottom, so White must defend. Next ...
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  VAR
  B 1 O6
  COM
  Failure.

  Pushing from behind with Black 1 ...
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  W 2 N7
  B 3 N6
  W 4 M7
  B 5 M6
  COM
  ... to 5 is bad style.
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  W 6 M4
  COM
  White defends the bottom with 6 and Black's stones are heavy
  and will have a hard time securing themselves.
  <=
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  ENDVAR
W 2 N4
  VAR
  W 2 O5
  COM
  Variation.

  If White plays 2 here, ...
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  B 3 O6
  COM
  ... Black can break through White's net with the sequence Black
  3, ...
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  W 4 N6
  COM
  ... White 4, ...
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  B 5 P7
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  ... Black 5.
  <=
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  ENDVAR
B 3 M5
W 4 M4
B 5 L5
W 6 K3
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... White secures the territory at the bottom with the sequence
to 6.
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B 7 Q11
COM
Black has sente, so he can turn his attention to the right side
and attack White's two stones there with 6. Black's moyo on the
right side is bigger than White's territory at the bottom, so
this is a good result for Black.
<=
ENDCOM