EVENT
BOARDSIZE 19
SETUP W D16 D4 
SETUP B Q4 Q16 
MARK 1@Q16 2@D16 4@D4 3@Q4
COM
Problem 45. Black to play.  

Both Black and White have made niren-seis. If Black wants to
make an approach move on the left, where should he play ? 
ENDCOM
B 1 F17
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black 1 is the usual approach move.
ENDCOM
W 2 D14
COM
If White answers with 2, ...
ENDCOM
  VAR
  W 2 H17
  MARK W@K4 B@Q10
  COM
  Depending on the circumstances.

  If Black had a sanren-sei formation on the right (suppose Black
  B - White W), the sequence in the Correct Answer might not be
  to White's liking because Black would have built up a large moyo.
  In that case, she would pincer with 2, ...
  ENDCOM
  B 3 C17
  W 4 D17
  B 5 C16
  W 6 D15
  B 7 D18
  W 8 E18
  B 9 C18
  W 10 E17
  COM
  ... making a thick position with the sequence to 10.
  ENDCOM
  B 11 C14
  COM
  <=
  ENDCOM
  ENDVAR
B 3 K16
MARK A@C6 A@C14
COM
... Black will extend to 3. Approaching between White's niren-sei
formation at the points A
D is rarely played.
<=
ENDCOM
  VAR
  B 3 D18
  MARK 2@D14
  COM
  Variation.

  In response to White 2, Black could also play the sequence from
  Black 3 ...
  ENDCOM
  W 4 C17
  B 5 J17
  COM
  ... to Black 5.
  <=
  ENDCOM
  ENDVAR