EVENT
BOARDSIZE 19
SETUP W C17 D16 C14 C13 C6 D4 O3 N2 O1 P2 Q2 R3 R17 R16 R14 S14 K16 L15 K14 M13 
SETUP B D13 D11 F3 M3 N3 O4 Q4 Q6 Q17 Q16 Q15 P13 R12 D18 F17 J17 J16 J15 K15 
MARK \t@K16 \t@L15 \t@K14 \t@M13
COM
Problem 27. Black to play.  

White has played lightly with the marked stones. How should Black
attack them ? 
ENDCOM
B 1 M11
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Capping with Black 1 is the best way to attack.
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  VAR
  B 1 L16
  COM
  Failure.

  If Black cuts at 1, ...
  ENDCOM
  W 2 M16
  COM
  ... White ataris at 2 and ...
  ENDCOM
  B 3 L17
  W 4 M15
  B 5 M17
  W 6 K12
  COM
  ... makes eye shape with the sequence to 6. White will now have
  no trouble making a living group in the center and Black has
  no prospects of making a moyo.
  <=
  ENDCOM
  ENDVAR
  VAR
  B 1 L14
  MARK \t@K16 \t@L15
  COM
  Failure.

  Black can capture the two marked stones by cutting at 1, but
  ...
  ENDCOM
  W 2 L13
  B 3 M14
  W 4 N14
  B 5 M15
  W 6 N15
  COM
  ... White can force with the sequence to 6, then ...
  ENDCOM
  B 7 M16
  W 8 O12
  MARK A@N16
  COM
  ... make shape with the knight's move of 8. White should have
  no trouble getting eyes for her group. It is now her privilege
  to play at A and Black's three stones at the top are in danger
  of being cut off.
  <=
  ENDCOM
  ENDVAR
W 2 K12
B 3 K10
COM
White will probably live, but, even if she does, Black will build
a large moyo below while attacking, and White will get minimum
territory.
<=
ENDCOM