EVENT
BOARDSIZE 19
SETUP W C16 B14 D17 F17 G18 H18 J17 C6 C3 D3 F3 Q6 O6 Q12 O13 M11 O15 O16 O17 
SETUP B H17 H16 J15 F16 E16 D14 D9 B6 C5 D6 D4 Q4 O4 M4 M17 M15 P17 Q16 Q14 S15 
COM
Problem 130. Black to play.  

This position arose from the Correct Answer in Problem 75. Where
should Black attack ? 

[You will find a supplement to this Problem Diagram as "Problem 149"]
ENDCOM
B 1 R11
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black 1 is a severe invasion.
ENDCOM
W 2 R12
B 3 S12
W 4 S13
B 5 S11
W 6 R13
B 7 Q11
W 8 P12
B 9 R8
COM
Black's aim is to drive a wedge between White's positions above
and below with the sequence to 9.
ENDCOM
W 10 S6
B 11 P7
W 12 P6
B 13 O9
W 14 R3
B 15 R4
W 16 S4
B 17 O11
COM
Note Black 17.
ENDCOM
W 18 M14
COM
White must defend with 18 ...
ENDCOM
  VAR
  W 18 N12
  COM
  If White responds with 18 here, 
  ENDCOM
  B 19 N14
  COM
  ... Black will peep at 19, ...
  ENDCOM
  W 20 O14
  B 21 O12
  MARK A@P13 B@N13
  COM
  ... then play 21. The points A and B are now miai, so White can't
  avoid losing some stones.
  <=
  ENDCOM
  ENDVAR
B 19 L15
W 20 M13
COM
... and 20, inducing Black to strengthen his stones there.
ENDCOM
B 21 M9
COM
After Black 21, White's stones are without eyes in a sea of Black
influence.
<=
ENDCOM