EVENT
BOARDSIZE 19
SETUP W C18 D17 E18 E16 K16 K17 L17 K14 R14 R9 R6 D3 E3 C4 C6 C10 
SETUP B C17 C16 C15 L16 M16 M14 N17 R16 Q16 R4 Q3 K4 C12 E4 F4 F3 
MARK \t@K14
COM
Problem 109. Black to play.  

White has jumped into the center with the marked stone. What
should Black do ? 
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B 1 R11
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black is strong above and below, so he can invade White's thin
position with 1.
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W 2 Q12
B 3 Q11
W 4 O12
B 5 P11
W 6 P12
B 7 M12
W 8 O11
COM
If White plays the sequence to 8, ...
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B 9 Q9
COM
... Black leans on the white stone below with 9. Next ...
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W 10 Q8
MARK \t@Q9
COM
... White answers the marked stone with 10.
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B 11 P9
W 12 N10
B 13 P8
W 14 Q7
B 15 S9
W 16 S8
B 17 R10
W 18 R8
B 19 N8
W 20 L10
B 21 S5
W 22 S10
B 23 S11
W 24 T9
B 25 P5
W 26 S6
COM
When White plays 26, her stones are alive, but Black has built
up a moyo at the bottom.
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B 27 K13
COM
After 27, White's stones are still insecure.
<=
ENDCOM