Main line
The descent at is key for life. If makes a placement, then and forms a seki. This is the main line.
Life
If plays the hane, then divides the eye space into two eyes very nicely. White cannot cut at a because of shortage of liberties.
Black's failure 1
Descent on the wrong side. The points a and b are miai for the kill.
Black's failure 2
is a greedy move that fails. followed by the throw-in at reduces Black to only one eye.
Karl Knechtel, unkx80
See also:
Referenced byBeginnerExercise56