EVENT
BOARDSIZE 19
SETUP W D16 C4 D3 R9 R14 S16 
SETUP B C6 C9 P3 R4 R17 Q16 O17 
MARK \t@R17
COM
Problem 77. White to play.  

After Black defends the corner with the marked stone, where should
White play ? 
ENDCOM
W 1 Q12
MARK \t@R9
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

The marked white stone is far way from its allies above, so White
should defend at 1, which makes a good high-low balance.
ENDCOM
  VAR
  W 1 C11
  COM
  Failure.

  White 1 is certainly a good attacking move, but ...
  ENDCOM
  B 2 R12
  COM
  ... Black will invade at 2.
  ENDCOM
  W 3 P14
  B 4 P12
  W 5 N14
  COM
  After the sequence to White 5, ...
  ENDCOM
  B 6 R7
  COM
  ... Black takes the initiative on the right side with the checking
  extension of 6.
  <=
  ENDCOM
  ENDVAR
B 2 C13
COM
Black 2 is also a good move.
ENDCOM
W 3 K3
MARK A@F17
COM
Next, White extends along the bottom with 3, but White 3 at A
would also be big.
<=
ENDCOM