Beginner Exercise 164 / Solution

at  

and ! is the key. This squeeze is a fairly standard sequence. If at then captures at .

(In fact, there is something similar in one of the small nadare josekis.)

at  

White may sacrifice the three stones to live in the corner, but Black's stones all become connected and strong, while White's left group still needs to crawl on the second line for life. Black is much better.

Failure

Failure  

Unfortunately, looking at how to refute is not as easy as it seems. is the tesuji.

Failure  

If connects, then the hane at kills.

Failure  

Due to shortage of liberties, cannot connect at .