Beginner Exercise 18 / Solution

Solution  

The only solution for Black to save himself is to fight the ko at a with .

Analysis of ko

If Black wins the ko  

If Black wins the ko at a by capturing at , he lives.

If Black loses the ko  

If Black loses the ko, the White connects at , creating a dead shape and thereby kills the entire Black group.

If Black loses the ko  

Even if Black gets to play the stones to expand the eye space to the maximum, Black is still dead. If Black actually played at a, then Black dies with a farmer's hat dead shape. Otherwise, White can almost fill the Black group with a bulky five dead shape by playing at a.

Failure

Failure  

If , then kills. See the analysis of ko section above for the reason.

Failure  

Similarly, if here, kills.

Failure  

Same thing. This shows that is a vital point for White for the kill.

Failure  

is a mistake, and kills by turning the group into a bent three dead shape.