Beginner Exercise 193 / Solution

Analysis  

Before presenting the solution proper, it is worth nothing that aims at in this diagram. This is going to spell trouble for Black, the result is at least a favourable ko for White. So Black at a definitely is not going to be a solution.

Failure  

However, playing directly at is also wrong. While it is not possible for White to approach at a, White can play at . If blocks, White can start a ko with .

Failure  

If makes an eye here, then White has successfully made a seki in sente within Black's territory.

Failure  

Actually, if White wants to avoid a ko at all costs, it is still possible to create a seki with and . But this seki is gote for White, and also White loses points due to sacrifice of and .

Failure  

If , then White has the option of playing for a peaceful seki or to start a ko at a. Or can just play elsewhere.

Solution  

By now, it should be clear that is the only solution. See that White a means self-atari.

Solution  

If , then can play elsewhere.

Solution  

tries to bluff Black into thinking there is a ko. shows that with a connect-and-die, there isn't any ko.

NecRock?: Would it be a good idea for Black to take the ko anyway, once, to make White waste a threat?

unkx80: Not necessary a good idea. White can just play elsewhere, and then locally White has one more ko threat than before.

Eaglehelm: Not even a ko. The move captures two stones.