EVENT
BOARDSIZE 19
SETUP W B17 C17 D16 E16 G17 R10 P10 R6 Q6 Q5 D4 C6 C10 D10 
SETUP B L17 P16 R16 R12 R5 R4 Q3 P4 K4 F3 F5 C12 C16 C15 E14 
MARK A@E12 B@F5
COM
Problem 107. White to play.  

Instead of securing his stones at A, Black jumps to B. How should
White attack the black stones on the left ? 
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W 1 D13
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

White 1 is the vital point.
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B 2 C13
COM
If Black defends at 2, ...
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W 3 D14
COM
... White plays 3 ...
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B 4 D15
W 5 E15
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... and 5. and the black stones are in trouble. White is threatening
to play A, but, if Black defends there, his stones will have
a hard time making two eyes.
<=
ENDCOM