EVENT
BOARDSIZE 19
SETUP W D16 F17 R14 Q11 E10 G10 C9 D7 D6 C4 D3 C2 M5 M6 R5 N4 N3 M3 N2 F3 H3 G4 G3 G2 J3 J4 
SETUP B K16 Q16 S14 S15 D2 E3 F2 E4 F4 E7 E8 G5 H5 H4 J5 L5 L4 M4 N5 O5 O4 Q5 Q7 R4 Q3 
MARK \t@Q11 \t@R14
COM
Problem 79. Black to play.  

How should Black attack the marked white stones ? 
ENDCOM
B 1 O11
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Capping with Black 1 is best.
ENDCOM
  VAR
  B 1 R13
  COM
  Failure.

  Black 1 has no strategic significance.
  ENDCOM
  W 2 Q13
  B 3 R12
  W 4 O11
  COM
  White lightly jumps to 4 and Black no longer has an attack.
  <=
  ENDCOM
  ENDVAR
W 2 R9
COM
If White defends with 2, ...
ENDCOM
  VAR
  W 2 P13
  COM
  If White 2 here, ...
  ENDCOM
  B 3 R9
  COM
  ... Black plays 3 here and White's stones will come under attack.
  <=
  ENDCOM
  ENDVAR
B 3 P13
COM
... Black plays 3 and a moyo begins to appear at the top.
<=
ENDCOM