EVENT
BOARDSIZE 19
SETUP W D18 F17 H16 K16 M17 R14 Q14 Q10 
SETUP B C17 D16 C14 O17 O16 Q16 R15 
COM
Problem 148. White to play.  

Black's formation is very tight. Is it possible for White to
invade here ? 
ENDCOM
W 1 R17
USER
CORRECT ANSWER
ENDUSER
COM
Correct Answer.

White's invasion at 1 is unreasonable.
ENDCOM
B 2 S15
COM
Black blocks at 2 and ...
ENDCOM
W 3 P18
B 4 O18
W 5 P17
  VAR
  W 5 Q18
  COM
  Variation.

  If White draws back with 5, ...
  ENDCOM
  B 6 T18
  COM
  ... Black's killing move is at 6. From this diagram it is easy
  to see just how big Black's territory is.
  <=
  ENDCOM
  ENDVAR
B 6 P16
W 7 S18
B 8 P19
W 9 Q18
B 10 T17
COM
... after Black 10 it is clear that White is dead.
<=
ENDCOM