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zero in CGT terms
Path: CGTPath   · Prev: EqualityOfGames   · Next: OrthodoxPlay
   

How do you recognise go positions that are equal to 0, in the sense of CGT? Since the idea of number appropriate in CGT corresponnds to territory in go, zero games should comprise positions recognisable as 'no net territory for anyone'.


Here is a 0 in go:

[Diagram]
Diag.: Zero (Seki)

One way to write it is

                    { 6 | -10 || 8 | -8 }

If Black plays first White can reply and get 10 points (White scores are negative); if White plays first Black can reply and get 8 points. Neither player can afford to play.

Here is another 0, this time a clear case of miai:


[Diagram]
Diag.: Zero

We can write it

                    { 2 | 0 || 0 | -2 }.

In this case neither player can gain by playing here.



Note on the diagrams: When we're getting picky, it's important to indicate where the plays are. So instead of the usual convention of surrounding positions by open points, I have surrounded them by empty space or by nothing. The stones that frame the position cannot be captured. See assumptions of yose problems.


Original page by Bill Spight, moved and edited by Charles Matthews.



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