Beginner Exercise 238 / Solution

White kills  

atari serves two purposes - preventing escape to the center and reducing the group's liberties. If connects, kills easily. at a also kills.

Variation 1  

If captures, then kills. at a dies in gote - even after that, he can't play at b for shortage of liberties.

Variation 2  

Although can capture two White stones, Black has only one eye after .

Failure  

is a mistake. After , a living and b escaping are miai.