ShuntProblem1/Solution

Sub-page of ShuntProblem1

Charles As was suggested, start like this.

[Diagram]

Solution



You might think this is 'obvious'; but one does have to think about Black playing at a first. And for that you have to read on.

JoelR: It doesn't matter to the shunt line, but BS has evaporated in all the diagrams below. Do we mind?

[Diagram]

Making a ko?



As Bill pointed out, W2 here is better than connecting, which would get an immediate shunt to capture. So will this be a ko?

[Diagram]

Ko line



If White contests this ko, Black has a useful threat at a. Suppose Black wins the ko.

[Diagram]

Winning the ko (1)



One has to imagine this position, right at the start, to see how serious it is, when Black connects with BS. This is shown with the BC/WC exchange made.

[Diagram]

Winning the ko (2)



And without it. Here B3 will end in sente, because there is now a weakness at b. But can White afford W2?

[Diagram]

Winning the ko (3)



Yes, that's OK in fact; Black has nothing after W4.

So, in conclusion, not only shouldn't Black play atari blindly here, it is better not to play it unless Black will also lose the ko. (Another example of a local threat that diminishes the ko, If I'm not wrong.)


[Diagram]

Conceding



In practice White may well concede with W1. White ends in sente. There is no reason for Black to waste ko threats with an atari here.


This is a copy of the living page "ShuntProblem1/Solution" at Sensei's Library.
(OC) 2005 the Authors, published under the OpenContent License V1.0.
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