Beginner Exercise 140 / Solution

Sub-page of BeginnerExercise140

Solution

[Diagram]

Two stage ko.

The solution to this problem is 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 direct ko, and the White group is extremely heavy.

[Diagram]

Direct ko.

The descent at W2 is not good too, as it leads to a direct ko too.



Failure

[Diagram]

Failure.

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.

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



Discussion

The following discussion is pitched at a slightly higher level than the problem, but it is still revelant to the problem.

[Diagram]

Discussion.

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

[Diagram]

Discussion.

So without Black a, Black should atari at B1. The correct response is W2, regardless of whether there is a Black stone at a. This is probably a IGS 1k* level indicator.



This is a copy of the living page "Beginner Exercise 140 / Solution" at Sensei's Library.
(OC) 2007 the Authors, published under the OpenContent License V1.0.
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