EVENT
BOARDSIZE 19
SETUP W D17 C15 G17 L16 N17 R13 R10 Q9 R7 D4 
SETUP B J16 P17 R15 Q16 P13 P10 O8 R8 P3 R4 
MARK \t@R7
COM
Problem 39. Black to play.  

White attaches with the marked stone in order to rescue her stones
under siege. How should Black respond ? 
ENDCOM
B 1 Q8
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black should push up with 1 and separate the white stones.
ENDCOM
  VAR
  B 1 S7
  COM
  Failure.

  If Black hanes at 1, ...
  ENDCOM
  W 2 Q8
  B 3 R6
  W 4 Q7
  B 5 S9
  W 6 Q6
  B 7 Q5
  W 8 O6
  COM
  ... White will escape into the center with the sequence to 8.
  <=
  ENDCOM
  ENDVAR
W 2 P9
COM
If White 2, ...
ENDCOM
  VAR
  W 2 S8
  COM
  Variation.

  But White could hane with 2, ...
  ENDCOM
  B 3 S9
  COM
  ... Black will block with 3 and, ...
  ENDCOM
  W 4 R9
  COM
  ... if White cuts with 4, ...
  ENDCOM
  B 5 S10
  COM
  ... Black will crawl to 5. This is quite a severe move.
  ENDCOM
  W 6 S11
  COM
  If White 6 here, ...
  ENDCOM
    VAR
    W 6 S7
    COM
    If White connects at 6, ...
    ENDCOM
    B 7 R11
    COM
    ... Black plays 7. Either way, White's position has collapsed.
    <=
    ENDCOM
    ENDVAR
  B 7 S7
  COM
  ... Black will capture a stone by playing at 7.
  <=
  ENDCOM
  ENDVAR
B 3 P8
COM
... Black could play 3 and secure the territory on the lower
right side.
<=
ENDCOM