(No. 165: June 21, 1999)
Elementary level: Answer
Black 1, sacrificing a stone, is crucial.
After White 2, Black wins the capturing race with 3 to 5.
Elementary level: Wrong Answer
Black 1 is wrong and loses the race with White 2.
Intermediate level: Answer
Black 1 is the vital point. After White 2,
Black kills White with the moves 3 to 7,
just like the preceding problem.
Intermediate level: Variation
If White 2, Black kills White with 3 and 5.