EVENT
BOARDSIZE 19
SETUP W B16 C14 C11 R14 Q10 K18 
SETUP B C17 D16 F16 K16 O16 Q16 
MARK 1@K18
COM
Problem 63. Black to play.  

White invades at 1. Although on the second line, it is a vital
point of this formation. How should Black respond ? 
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B 1 K17
USER
CORRECT ANSWER
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COM
Correct Answer.

Black 1 is the vital point.
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  VAR
  B 1 L17
  COM
  Failure.

  The diagonal move of Black 1 is lukewarm.
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  W 2 L18
  COM
  White first pushes into Black's side with 2, ...
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  B 3 M17
  W 4 H17
  COM
  ... then jumps to 4.
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  B 5 H16
  COM
  After Black attaches with 5, ...
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  W 6 G17
  B 7 G16
  W 8 E18
  MARK 8@G17
  COM
  ... White easily lives with 6 and 8.
  <=
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  ENDVAR
W 2 H17
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If White jumps to 2, ...
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  VAR
  W 2 J18
  COM
  Variation.

  If White extends to 2, ...
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  B 3 L18
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  ... Black still blocks at 3.
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  W 4 H17
  COM
  After the exchange of White 4 ...
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  B 5 H16
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  ...for Black 5, White can live, but this time Black gets both
  territory at the top right and thickness in the center.
  <=
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  ENDVAR
B 3 L18
COM
... Black will block off the territory at the top right with
3.
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W 4 H15
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White then escapes into the center with 4, ...
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B 5 F14
COM
... and Black follows suit with 5. Black gets territory and White
is still under attack.
<=
ENDCOM