Xuanxuan Qijing Problem 309 / Solution

 

There are two main features to notice in this problem.

1st  

First feature: this shape (Xuanxuan Qijing Important Shape 1) can be reduced to 1 eye.

2nd ( and at , at )  

Let's look at the corner next. (All these numbers basically translated to "black captures some white stones by snapback in the corner".)

2nd cont.  

Second feature: Although there's a snapback capture in the corner, black can't make an eye with it.
See also Xuanxuan Qijing Problem238 for another problem with this shape.

Failure

 

This is connect and die.

 

Any other move, black can simply secure enough eye space with 'a'.