Kyu Exercise 73 / Solution
The solution is . This makes a and b miai.
If descends, then can make the second eye on the left side. The eye on the right side is unaffected.
Similarly, if at a, then the same makes two eyes and lives.
here is a mistake, because after , Black is unable to play at to make a second eye due to shortage of liberties. The result is a ko for life.
Note that is the only correct move after , any other move dies.