EVENT
BOARDSIZE 19
SETUP W D16 D14 C10 D4 K3 O3 
SETUP B Q4 R6 Q16 Q14 F17 K17 
COM
Problem 69. Black to play.  

Each side has staked out his sphere of influence. However, Black
must now invade White's moyo. Where should he play ? 
ENDCOM
B 1 C3
MARK A@K5 A@E10 \t@K3 \t@C10
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black should invade the lower left corner with 1. Since both
the marked stones are on the third line, White can't expect to
make a large-scale moyo because Black can cap at one of the points
marked A.
ENDCOM
  VAR
  B 1 Q10
  COM
  Failure.

  If Black continues to map out his own territory by taking the
  big point at 1, ...
  ENDCOM
  W 2 F4
  MARK A@D6
  COM
  ... White will defend her position with 2 (or A) and Black will
  have a harder time erasing White's moyo. That is not to say that
  Black has a bad position, but he has lost his chance to decisively
  take the lead.
  <=
  ENDCOM
  ENDVAR
W 2 D3
COM
If White blocks with 2 and ...
ENDCOM
  VAR
  W 2 C4
  COM
  Variation.

  White could also block from the other side with 2.
  ENDCOM
  B 3 D3
  W 4 E3
  B 5 E2
  W 6 F3
  B 7 F2
  W 8 G3
  B 9 B4
  W 10 B5
  B 11 B3
  W 12 C6
  B 13 G14
  MARK B@K5 B@E10 A@G15
  COM
  This time, however, Black will map out his moyo at the top with
  13. This move also neutralises White's thickness below. If Black
  omits this move, White will map out a large-scale moyo by playing
  at A. After 13, Black still has the capping moves at the points
  B.
  <=
  ENDCOM
  ENDVAR
B 3 C4
W 4 C5
B 5 B5
W 6 C6
B 7 B6
W 8 C7
B 9 D2
W 10 E2
B 11 C2
W 12 F3
COM
... plays the sequence to 12, ...
ENDCOM
B 13 O5
COM
... Black will cap at 13 to build his own moyo on the right and
prevent White from making one herself.
<=
ENDCOM