Two by four box
Path: LifeAndDeath
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Keywords: Life & Death
1. No outside liberties
![[Diagram]](../../diagrams/44/f4a42b0b4b1e7ecfaeef2c40ddad5626.png) | No outside liberties |
If there are no outside liberties, White can make a sente seki.
![[Diagram]](../../diagrams/22/0d69864338ef63dc9366ea41aec0911e.png) | Main line |
is the strongest attack. is the vital point. is necessary or White plays there (or to the right of it) to capture the corner.
![[Diagram]](../../diagrams/38/bdf9b4a4954a3458dcb1c6c6f123f79e.png) | Variation at 4 |
If here, makes a thousand year ko. This result is generally worse for Black than a seki.
![[Diagram]](../../diagrams/21/d3dd836b2b4d3a3fdbe0e7a84cde5597.png) | Variation at 2 |
at the 2-2 point invites another thousand year ko.
![[Diagram]](../../diagrams/23/8bccac563ba80ba59b297d71a6cfc482.png) | Variation at 2 - White's mistake |
in this variation spoils the chance of a ko and invites a seki.
2. Outside liberties
![[Diagram]](../../diagrams/17/bbf421b6a808d75b70aab91bc8854075.png) | Outside liberties |
If there is at least one outside liberty, Black is alive with seven points.
![[Diagram]](../../diagrams/42/17d13d8f942ebb5b9477b53c6c98414e.png) | Main line |
Now and the throw in at work. creates shortage of liberties for White. (If there were no outside liberty, would be self-atari.)
Conclusion for the endgame
![[Diagram]](../../diagrams/19/121983d6efafe27d5d67ae546be4b28c.png) | Outside liberties |
threatens to destroy seven points in sente (assuming capturing the corner would decide the game). makes seven points in reverse sente. So,
is a typical ko-threat - but it is a bad one. In case of a ko the previous diagram supplies four ko-threats: that's one more than here.
Path: LifeAndDeath
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This is a copy of the living page
"Two by four box" at
Sensei's Library.
2003 the Authors, published under the OpenContent License V1.0.
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