Beginner Exercise 73 / Solution

A solution?  

Blake: After the marked stone has been played, I don't see how White can kill the group. It guarantees an eye at a.

Proofs I  

After a or b, White is either in atari or close to it.

Proofs II  

After , the eyes are obvious at a and b.

unkx80: can be played at c too.

Proofs III  

(Best for White.)

Failure  

Dansc: Enlarging the eyespace with fails. Black's eyespace is a bulky five, so kills the black group - a and b are miai for kill now. The bulky five shape is the same reason a black stone at would make the group alive.