(No. 390: October 13, 2003)
Black 1 is crucial. White dies.
This may be easy, but I once saw an amateur dan-player miss in a game.
Elementary level: Wrong Answer
Black 1 is wrong and allows
White to get a Ko with the moves 2 to 8.
Black 1 is crucial.
If White 2, Black lives with 3 to 9.
If White 4 at 5, Black lives with 7.
Intermediate level: Answer (Variation)
Black 1 first, and after White 2, Black 3 leads to the same result.
Intermediate level: Wrong Answer
Black 1 is wrong.
The result is a Ko with the moves White 2 to Black 11.