EVENT
BOARDSIZE 19
SETUP W C15 C16 C13 C7 D7 D6 D5 E3 Q3 R6 P17 J16 J14 
SETUP B D15 E17 E14 E12 C2 C4 C5 C6 L3 R16 Q15 O16 L16 
MARK \t@J14 \t@J16
COM
Problem 22. Black to play.  

What should  Black do about the marked stones at the top ? Pay
attention to Black's four stones on the left.  
ENDCOM
B 1 J12
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black should cap with 1.
ENDCOM
  VAR
  B 1 L14
  COM
  Failure.

  Chasing White into the center with Black 1 ...
  ENDCOM
  W 2 J12
  B 3 L12
  MARK \t@P17 \t@E17 \t@D15 \t@E14 \t@E12
  COM
  ... and 3 weakens the marked stones in the upper left. Not only
  are these stones in trouble, but the marked white stone in the
  upper right still has aji.
  <=
  ENDCOM
  ENDVAR
W 2 L14
COM
If White jumps to 2, ...
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B 3 O17
MARK \t@E17 \t@D15 \t@E14 \t@E12
COM
... Black secures the corner with 3. The important point here
is that the marked stones can't be easily attacked after Black
1, while White's stones at the top are still vulnerable.
<=
ENDCOM