Answers

(No. 256: Mar. 19, 2001)

Elementary level: Answer

Black 1 is crucial. If White 2,
Black cuts at 3 and wins the capturing race.
If White 2 at 3, Black is safe with 2.

Elementary level: Wrong Answer

Black 1 loses the capturing race with White 2.
If Black 1 at 2, White 1 kills Black.

Intermediate level: Answer

The combination of Black 1 and 3 is crucial
to kill White with the moves to 11.
(The same shape as the preceding problem)

Intermediate level: Wrong Answer

Black 1 first and then 3,
allows White to get a Ko with 4.