EVENT
BOARDSIZE 19
SETUP W E16 F16 F17 E14 E12 M16 Q4 D4 F4 
SETUP B C16 D17 E17 C14 H16 O16 R16 C3 B4 C6 
MARK A@K16 C@H14 B@J15 D@M14 \t@O16
COM
Problem 150. White to play.  

Black has just played the marked stone. How should White take
control of the situation at the top ? 
ENDCOM
W 1 J15
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

White should play the shoulder hit of 1. Black will now find
it hard to escape with his stone at the top.
<=
ENDCOM
  VAR
  W 1 K16
  COM
  Failure.

  If White plays 1 here, ...
  ENDCOM
  B 2 H18
  MARK A@H14
  COM
  ... Black jumps down to 2, threatening to link up to his stones
  on the left, then jumps to A.
  <=
  ENDCOM
  ENDVAR
  VAR
  W 1 H14
  COM
  Failure.

  If White caps with 1, ...
  ENDCOM
  B 2 K16
  COM
  ... Black can jump to 2.
  <=
  ENDCOM
  ENDVAR
  VAR
  W 1 M14
  COM
  Failure.

  White plays on a large scale when she jumps to 1, ...
  ENDCOM
  B 2 H13
  COM
  ... but when Black jumps out into the center, White finds her
  stones at the top split apart.
  ENDCOM
  W 3 K4
  COM
  White plays 3 to restore the territorial balance, but ...
  ENDCOM
  B 4 K16
  COM
  ... Black secures his stones with 4 ...
  ENDCOM
  W 5 M18
  B 6 K14
  COM
  ... and 6. White has a lost game.
  <=
  ENDCOM
  ENDVAR