Gokyo Shumyo, Section 1, Problem 9 / Solution

White to live  

prevents the capture of two stones and makes shape. She has to be careful in answering and .

Follow-up  

White should play . When atari, captures, and captures...

Continuation  

White can recapture at , and has two eyes at a and b.

Alternative follow-up  

The tesuji at works too.

Continuation  

After , it just transposes back to the previous solution.

Mistake in the follow-up  

If instead of throwing in, White blocks at , starts a ko.

Wrong  

on the 2-2 point doesn't give life. After the connection at , White still has only one eye in the corner. Black can also play atari with at .

Wrong (ii)  

Connecting at is the third way to save the two stones. Black plays hane at and makes a placement at - and White is dead, because now a and b are miai. Black could also kill by playing on the vital point of this shape, namely .

White to live  

ProtoDeuteric: Does this work?

unkx80: should play at for life, and should play at to kill with a bulky five.

 

go student: What about this. There should be at least a ko, as I can see. Please tell me if I miss something

atari at a or connect at below are clean kills