(No. 161: May 24, 1999)
Elementary level: Answer
Black 1, sacrificing one more stone is the vital point.
After White 2, to the next diagram.
Elementary level: Answer (Continued)
Black 3, sacrificing one more stone is crucial.
After White 4, Black gets a Ko with 5 and 7.
Elementary level: Wrong Answer
Black 1 is wrong. After White 2,
Black is captured unconditionally.
Intermediate level: Answer
The combination of Black's moves 1, 3 and 5 kills White.
This is the same shape as the preceding problem (No.160),
and White dies unconditionally.
Intermediate level: Variation
If White 2 and 4, Black 5 is crucial to kill White.
(The same shape as the problem No.159.)
Intermediate level: Wrong Answer
Black 1 fails. After White 2 and Black 3, White 4 is
the vital point to get a Ko with the moves to 10.
Intermediate level: Wrong Answer(Variation)
If Black 5, White 6 gets a Ko.