EVENT
BOARDSIZE 19
SETUP W G16 G17 J16 H13 F13 B16 B14 C14 D14 D15 D16 D4 
SETUP B B17 C18 D18 D17 F18 F17 F16 F15 C16 C15 B15 Q3 R16 O17 
MARK A@D7 C@K4 B@Q5
COM
Problem 129. White to play.  

Taking into account White's position in the upper left, where
do you think White should play ? 
ENDCOM
W 1 D7
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

White should extend to 1, making a moyo on the left side.
ENDCOM
  VAR
  W 1 K4
  COM
  Failure.

  White 1 is a big extension, but it is premature.
  ENDCOM
  B 2 C6
  MARK A@D12
  COM
  Black can approach at 2, as well as force with A, so White's
  moyo strategy will have failed.
  <=
  ENDCOM
  ENDVAR
B 2 J4
COM
This enables Black to make the good point of 2, ...
ENDCOM
W 3 Q5
COM
... but White can approach with 3, and, ...
ENDCOM
B 4 R5
W 5 R6
B 6 R4
W 7 Q6
B 8 O4
W 9 Q10
COM
... after the joseki to White 9, Black is unable to make a moyo
on the right side.
<=
ENDCOM