(No. 99: Mar. 16, 1998)
Elementary level: Answer
Black 1 is the vital point.
After White 2, Black 3 gets a Seki and lives.
Elementary level: Wrong Answer 1
Black 1 allows White to play 2 and get a Ko.
(This is a ten-thousand-year Ko.)
Elementary level: Wrong Answer 2
Black 1 is wrong. After White 2,
Black has no choice but to get a Ko with 3.
Intermediate level: Answer
Black 1, attacking from outside,
is crucial to destroy White's eye shape.
There is no way for White to live.
If White 2 at 5, Black 4 kills White.
This may look easy as a problem,
but I have seen an amateur Dan-holder miss it in a real game.
Intermediate level: Wrong Answer 1
Black 1 fails. It allows White to get two eyes with 2.
Intermediate level: Wrong Answer 2
Black 1 also fails. White lives with 2 to 10.
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