EVENT
BOARDSIZE 19
SETUP W C15 R3 C11 E3 F4 
SETUP B D17 R16 C4 D7 H4 
COM
Problem 17. Black to play.  

Black wants to keep the two white stones on the lower left unsettled.
How should he play ? 
ENDCOM
B 1 C3
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Descending to Black 1 is a solid move.
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  VAR
  B 1 D3
  COM
  Failure.

  Many player would instinctively attach with 1, but ...
  ENDCOM
  W 2 D2
  B 3 C2
  W 4 D4
  B 5 C3
  W 6 D5
  COM
  ... White would make shape with the sequence to 6.
  ENDCOM
  B 7 C6
  COM
  Black has to link up with 7, so ...
  ENDCOM
  W 8 K4
  COM
  ... White will be able to attack the black stone at the bottom
  with a pincer at 8.
  <=
  ENDCOM
  ENDVAR
  VAR
  B 1 L4
  COM
  Failure.

  If Black extends with 1, ...
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  W 2 C2
  COM
  ... White can settle her stones by sliding to 2. Black has failed.
  <=
  ENDCOM
  ENDVAR
W 2 F6
COM
White has to jump to 2, so ...
ENDCOM
B 3 L4
COM
... Black can take up a position at the bottom by extending to
3.
<=
ENDCOM