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AttritionMethod

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Method of playing inside systematically
  Difficulty: Beginner   Keywords: Tactics

[Diagram]
Diag.: White needs to capture

In a position of this kind, White may eventually need to capture the inner black stones. We aren't showing the complete situation of the marked white stones. Just suppose that White knows that this capture must be made at some time, perhaps nearly at the end of the game. Black's stones are dead as we see them - but how can White remove them?

The answer is that White must proceed in steps, reducing Black's liberties, which currently appear to be 4, but are better thought of as 5[1]. The first step is to reduce that number by 1.


[Diagram]
Diag.: White plays inside three times

By playing inside with White 1, 3 and 5, White puts Black into atari. Black must answer to save the stones, using Black 6 to capture. It doesn't help Black to play inside earlier than that.


[Diagram]
Diag.: Black captures

Black captures with 6. That leaves an unsettled group, so that White must answer immediately.


[Diagram]
Diag.: Unsettled group

This position is one in which Black can make two eyes, but it is White's turn. In fact White's objective was said to reduced Black to three liberties, and White has succeeded. But this is no time in which to forget to play here.


[Diagram]
Diag.: Black is still dead

White 7 is required, and also reduces Black from three liberties to two.



This attrition method [2] eventually succeeds in capturing Black, except in two circumstances:

  1. White doesn't have enough time (a capturing race); or
  2. Black can make two eyes.

But see attrition method mistake.

Charles Matthews


[1] Liberty is ambiguous. It can mean the number of empty points next to a stone or chain of stones (aka dame), or it can mean the net number of plays required to capture the chain. In this case the black chain has 4 dame but it takes 5 net moves to capture it.

Charles The net number of plays required to force the capture. Indeed. But this is a beginner page, and the distinction in question really has to wait until the 'method' is understood; after all the number you come up with does depend on it. At the start, say on Basic Rules of Go, liberty is what-you-see-is-what-you-get.

Bill: If you want to avoid ambiguity, say dame instead of liberty.

Charles Disagree. I think the root of this verbal problem is the absence of a special term for 'liberty in capturing race' in English. Not too late for that, I'd say.

unkx80: Why abandon the term approach moves?

Charles I don't think we should. The page we now have on it seems a little narrow, but it could be improved. At present I'm thinking that something like 'secondary liberty count' is suitable to include both approach moves and under-the-stones plays one should count. In some capturing races it is even more complicated than that.

Secondary liberties examples


[2]

Dieter: Continuing on my (re)quest for mercy on the non-native English speakers, I'd like to point out that a beginner who is no native English speaker is unlikely to think that a page called Attrition method is aimed at them. Although my English has often proven to be insufficient on this site, I think I can judge the matter by my own loss at understanding the term attrition, even though I'm blessed with an intensive Latin background.

Charles OK, something like 'systematic way to capture' might be a good alias/new title. 'War of attrition' is a common phrase in English.



This is a copy of the living page "Method of playing inside systematically" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.