Eye by Exhaustion

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    Keywords: Life & Death, Go term

Tamsin's term for the eye-making technique used in the following sample problem from the Korean Baduk Academy (on [ext] http://www.gobase.org/):

[Diagram]

Basic situation

[Diagram]

White's stones are too "exhausted" to move



And now White is unable to set up false eye-making throw-ins by playing either side of the WS stones, because that would be self-capture. [1] It seems to my mind that both the white stones are too "exhausted" to go one step further.

tderz: Why other attempts do not work [2].


[1] Correct me if I'm wrong, but I believe that self-capture is legal under Ing Rules, in which case the Eye By Exhaustion method would fail.

Dieter: It doesn't fail. Rules have seldom effect on life and death issues and shapes.

Tamsin: Ah, yes, of course, because Black still has sente after White captures herself. But the status of this example does become slightly unsettled under Ing Rules, because White can use self-capture as a ko threat:

[Diagram]

White's ko threat using self-capture

If Black now plays tenuki to win the ko, White can throw-in at W1, killing Black's group.

mgoetze: But the number of ko threats stays the same... under Japanese rules there are also ko threats against this group, and they are mutually exclusive with the "additional" ko threats provided by rules allowing suicide:

[Diagram]

Ko Threats...

Threatening at a eliminates the threat at b, threatening at c eliminates the threat at d.

Tamsin: Yup, indeed. Two contrasting ways to the same end.

Andrew Grant: But sometimes there is a difference.

[Diagram]

No Threats...

In this position White has no threats under Japanese rules, but still two at a and b under Chinese rules.

iopq: You mean Ing Rules?


See also:


[2]

[Diagram]

Question: why not like this?

tderz: why not like this?

[Diagram]

tderz: White's W2 is useless, because afterwards neither White a or b work.

[Diagram]

ko

tderz: If B3 and W4, the ko ( B5 ) has to be fought...

[Diagram]

idea behind it is ishinoshita

tderz: ishinoshita is the idea behind it. It still would be ko ... if not ...

[Diagram]

idea behind it is ishinoshita

tderz: ... more important, ishinoshita does not work because the cutting point c is protected
and there was no time to extend to below.

[Diagram]

tderz: ... i.e., preparing ishinoshita-shape is not replied by d but finished off with W4.

Black cannot connect at e.



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