EVENT
BOARDSIZE 19
SETUP W D16 Q9 O9 O11 O7 J3 L3 M3 N3 Q3 P3 
SETUP B C4 Q16 Q13 Q11 R5 P4 O5 M4 L4 K4 M7 M9 
MARK B@R7 A@C10 C@E3
COM
Problem 127. White to play.  

A sharp exchange took place on the lower right. It is White's
move. Should she leave the right side as it is and play at A
or C, or does she need to play a move at B ? 
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W 1 R7
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Before anything else, White must secure her position on the lower
right by playing on the urgent move of 1.
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  VAR
  W 1 C10
  COM
  Failure.

  If White plays on the left side with 1 or approaches the stone
  in the lower left, ...
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  B 2 R7
  COM
  ... Black will play 2, robbing White's stones of their base.
  These stones will now come under a severe attack.
  <=
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  ENDVAR
  VAR
  W 1 E3
  COM
  Failure.

  Also wrong.
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  B 2 R7
  COM
  Black attacks with 2.
  <=
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  ENDVAR
B 2 C14
W 3 F17
B 4 G16
W 5 G17
B 6 J16
W 7 H16
B 8 H15
W 9 H17
B 10 J15
W 11 R17
B 12 R16
W 13 C10
COM
The sequence to 13 is one possible continuation.
<=
ENDCOM