White enlarges her eye space with , then makes eye shape with
.
Incidentally,
and
makes a notcher with code 411WN.
If White descends at a instead of move , then White is also alive. However this way is less good for White, as Black can profit by capturing two stones. See problem 28 in this series for details.
The solid connection at fails. Black a to d all kill. (This shape is coded 312NS notcher.)
If White enlarges her eyespace, there are many ways to kill. For example, and
leads to some nakade shape.