EVENT
BOARDSIZE 19
SETUP W D16 Q4 P17 L17 
SETUP B C4 E3 R16 Q15 
MARK C@R10 B@C10 D@L3 A@F17
COM
Problem 141. Black to play.  

At the beginning of the game, you have to play the best move
or your opponent may seize the initiative. Where is Black's biggest
move ? 
ENDCOM
B 1 C10
MARK A@L3 \t@E3
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black 1, extending from his corner enclosure below, is the most
effective move. Since the marked stone is on the third line,
Black's position at the bottom would be too low if he played
at A.
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  VAR
  B 1 L3
  COM
  Failure.

  Black's position at the bottom is too low.
  <=
  ENDCOM
  ENDVAR
  VAR
  B 1 R10
  COM
  Failure.

  If Black extends to 1 here, ...
  ENDCOM
  W 2 C9
  COM
  ... White will switch to the left side with 2, and, ...
  ENDCOM
  B 3 C14
  W 4 C15
  B 5 D14
  W 6 F16
  B 7 C11
  W 8 C6
  COM
  ... after the sequence to White 8, the value of the Black corner
  enclosure is diminished.
  <=
  ENDCOM
  ENDVAR
  VAR
  B 1 F17
  COM
  Failure.

  Approaching inside White's sphere of influence with 1 is not
  good at this early stage of the fuseki.
  <=
  ENDCOM
  ENDVAR
W 2 Q11
B 3 R6
W 4 R5
B 5 Q6
W 6 O4
B 7 Q9
COM
The game continued with the sequence to Black 7.
<=
ENDCOM