(No. 193: Jan. 3, 2000)
Elementary level: Answer
Black 1 is the vital point to win the capturing race.
Elementary level: Wrong Answer
Black 1 allows White to play on the vital point 2
and cannot win the race.
Intermediate level: Answer
Black 1 and 3 is a set of Tesuji.
After White 4, Black gets a Ko with 5.
Intermediate level: Wrong Answer
Black 1 is wrong. White plays 2 to 8,
and Black loses the capturing race.