Beginner Exercise 193 / Solution

Sub-page of BeginnerExercise193
[Diagram]
Analysis  

Before presenting the solution proper, it is worth nothing that white+circle aims at W1 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.

[Diagram]
Failure  

However, playing directly at B1 is also wrong. While it is not possible for White to approach at a, White can play at W2. If B3 blocks, White can start a ko with W4.

[Diagram]
Failure  

If B3 makes an eye here, then White has successfully made a seki in sente within Black's territory.

Bill: When White can win the ko, Black will avoid it with B3.

[Diagram]
Failure  

Actually, if White wants to avoid a ko at all costs, it is still possible to create a seki with W2 and W4. But this seki is gote for White, and also White loses points due to sacrifice of W2 and W4.

Bill: Late in the game (where this position is likely to arise), this is the way for White to play if Black can win the ko.

[Diagram]
Failure  

If B3, then White has the option of playing W4 for a peaceful seki or to start a ko at a. Or W4 can just play elsewhere.

[Diagram]
Solution  

By now, it should be clear that B1 is the only solution. See that White a means self-atari.

[Diagram]
Solution  

If W2, then B3 can play elsewhere.

[Diagram]
Solution  

W2 tries to bluff Black into thinking there is a ko. B3 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.



Beginner Exercise 193 / Solution last edited by Eaglehelm on December 26, 2009 - 02:03
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