EVENT
BOARDSIZE 19
SETUP W D16 K16 O17 D4 O3 O5 Q2 
SETUP B Q16 Q14 L4 Q4 Q6 R3 Q10 
MARK A@L2 7@L4 4@D4 2@D16 14@K16 12@O17 1@Q16 13@Q14 5@Q10 9@Q6
MARK 3@Q4 11@R3 8@O5 6@O3 10@Q2
COM
Problem 18. Black to play.  

After Black 11, White has neglected to complete the joseki by
sliding to A. How should Black punish White for this omission
? 
ENDCOM
B 1 N4
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black should peep with 1 ...
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  VAR
  B 1 C10
  COM
  Failure.

  Black would like to establish a presence on the left by playing
  at 1, but ...
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  W 2 L2
  COM
  ... White would then be able to settle her stones at the bottom
  by sliding to 2.
  <=
  ENDCOM
  ENDVAR
W 2 O4
B 3 N3
COM
... and rob White of her eye shape with 3.
ENDCOM
W 4 O2
COM
If White descends to 4, ...
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  VAR
  W 4 H4
  COM
  If White 4 here, ...
  ENDCOM
  B 5 O2
  COM
  ... Black will hane at 5, leaving the white stones eyeless and
  under a severe attack.
  <=
  ENDCOM
  ENDVAR
B 5 G3
COM
... Black will take up a position at the bottom by extending
to 5.
<=
ENDCOM