EVENT
BOARDSIZE 19
SETUP W D16 D14 D9 C7 C6 D3 D4 D5 E2 F3 K4 N4 
SETUP B D18 F17 F15 B6 C5 C4 C3 C2 D2 Q5 Q3 R9 Q16 
MARK B@F13 A@O17 C@B7 D@N7
COM
Problem 145. White to play.  

Black has a lot of profit, while White has thickness in the center.
However, Black is also threatening to build a moyo in the center.
Where should White play in this position ? 
ENDCOM
W 1 F13
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Capping with 1 is the biggest move.
ENDCOM
  VAR
  W 1 O17
  COM
  Failure.

  Against White 1, ...
  ENDCOM
  B 2 M17
  COM
  ... Black pincers with 2 and ...
  ENDCOM
  W 3 R17
  COM
  ... White must invade with 3.
  ENDCOM
  B 4 Q17
  W 5 R16
  B 6 Q15
  W 7 Q18
  B 8 P18
  W 9 R18
  B 10 P17
  W 11 R14
  COM
  But, after 11, ...
  ENDCOM
  B 12 F13
  MARK A@D12
  COM
  ... Black jumps to 12, aiming at A, so White must defend.
  <=
  ENDCOM
  ENDVAR
  VAR
  W 1 B7
  COM
  Failure.

  White 1 here is big, but gote.
  <=
  ENDCOM
  ENDVAR
  VAR
  W 1 N7
  COM
  Failure.

  White 1 is another moyo focal point, but ...
  ENDCOM
  B 2 F13
  COM
  ... Black 2 leaves White's moyo wide open.
  <=
  ENDCOM
  ENDVAR
B 2 O16
COM
If Black defends the upper right with 2, ...
ENDCOM
W 3 M9
COM
... White will stake out a vast moyo and wait for Black to try
to invade.
<=
ENDCOM