EVENT
BOARDSIZE 19
SETUP W D16 D17 D14 C12 B13 C5 D4 D3 C2 H4 G3 K3 S4 S6 T6 T7 R7 R8 S8 R9 R10 Q10 R11 S11 R12 R16 S16 R19 Q19 Q18 Q17 P17 P16 P15 N18 N17 M17 L17 L16 L18 K18 H18 H10 O9 H9 
SETUP B B12 C10 C7 P3 R4 R6 D2 E3 G4 R5 S5 T5 S12 T13 S14 S15 R15 Q15 Q16 R17 S17 R18 S19 O15 O14 N16 M16 O18 J18 J17 K17 K16 K15 L15 F17 F15 G11 Q9 P9 P10 P8 Q11 Q12 G10 
MARK \t@H4
COM
Problem 115. Black to play.  

White has just played the marked stone. What should Black do
? 
ENDCOM
B 1 G5
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

Black should extend to 1.
ENDCOM
  VAR
  B 1 F4
  COM
  Failure.

  In the game, Black drew back with 1, and ...
  ENDCOM
  W 2 H5
  COM
  ... White exchanged 2 ...
  ENDCOM
  B 3 F6
  COM
  ... for 3.
  ENDCOM
  W 4 D7
  COM
  Attaching with White 4, however, was a mistake.
  ENDCOM
    VAR
    W 4 H7
    MARK \t@F6
    COM
    White's best move.

    After Black jumped with the marked stone, White should have jumped
    to 4, linking up with her two stones in the center. White now
    has a won game.
    <=
    ENDCOM
    ENDVAR
  B 5 H7
  COM
  Black again goes on the offensive with 5.
  ENDCOM
  W 6 G9
  B 7 D6
  W 8 C6
  COM
  The game continued to White 8.
  <=
  ENDCOM
  ENDVAR
W 2 H5
COM
If White 2, ...
ENDCOM
B 3 H6
COM
... Black hanes with 3.
ENDCOM
W 4 G6
COM
When White cuts with 4, ...
ENDCOM
B 5 G7
W 6 F6
B 7 F7
MARK 5@G7
COM
... Black plays 5 and 7.
ENDCOM
W 8 E6
COM
White must play 8n to save her two stones, so ...
ENDCOM
B 9 J6
MARK \t@H9 \t@H10
COM
... Black extends to 9, trapping the two marked stones.
<=
ENDCOM