Beginner Exercise 140 / Solution

Sub-page of BeginnerExercise140

Solution

[Diagram]

Two stage ko.

B1, makuri, leads to a two stage ko. If White cannot win this ko, then he can back out with a subsequently.

[Diagram]

White dumpling.

A connection at W4 is highly undesirable for White. After B5, the ko becomes a much larger direct ko.

[Diagram]

Direct ko.

The descent at W2 is not good too, as it leads to a direct ko too. Or Black may play B3 at a, capturing two stones in sente.


Failure

[Diagram]

Failure 1

The atari at B1 is a failure. Instead of capturing at a, White can descend at W2 and there is nothing else Black can do.

[Diagram]

Failure 2

The atari at B1 here does not work either. The key move for White is W4, which prevents the ko.



Reference

[Diagram]

If not for the cutting stone

Without the black stone at a, B1 is a mistake - W2 can extend and say arigato to Black for the free gift. Obviously White should not play W2 at b - Black will play B2 at W2 and thank White instead.

[Diagram]

Reference

So without Black a, Black should atari at B1. The correct response is W2, regardless of whether there is a Black stone at a.



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