EVENT
BOARDSIZE 19
SETUP W E17 D17 C16 D15 P18 P17 P16 Q17 R17 S17 S16 O15 P14 R14 D3 D5 N3 O3 Q3 R3 S3 S4 R6 
SETUP B F16 E16 F17 K17 O18 O17 O16 R16 Q16 Q15 P15 S15 S14 R13 Q12 K3 N5 P4 Q4 R4 R5 S5 Q6 
MARK \t@Q17
COM
Problem 110. Black to play.  

White has just secured her corner by connecting with the marked
stone. What should Black do next ? 
ENDCOM
B 1 N15
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black should atari with 1, ...
ENDCOM
W 2 O14
B 3 O12
COM
... then attack with 3.
ENDCOM
  VAR
  B 3 N14
  COM
  Failure.

  Black could drive the white stones toward the bottom with 3.
  ENDCOM
  W 4 P12
  B 5 P11
  W 6 O12
  B 7 M12
  W 8 O11
  B 9 P10
  W 10 O10
  B 11 P9
  COM
  Black secures territory on the right with 11.
  ENDCOM
  W 12 M10
  B 13 K11
  MARK \t@D15
  COM
  After 13, White's stones are still in danger, but Black's moyo
  at the top is wide open and, with the marked stone in place,
  its scope is limited.
  <=
  ENDCOM
  ENDVAR
W 4 N14
B 5 M15
W 6 M14
MARK 4@N14
COM
White runs away with 4 and 6, ...
ENDCOM
B 7 L15
MARK 5@M15
COM
... inducing Black to secure his territory at the top with 5
and 7.
ENDCOM
W 8 M12
COM
Next, White jumps to 8 and ...
ENDCOM
B 9 N10
COM
... Black turns his moyo on the right into territory.
<=
ENDCOM