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LifeAndDeath

 

Two by four box
Path: LifeAndDeath   · Prev: TwoByThreeBox   · Next: WalkieTalkieSeven
    Keywords: Life & Death

1. No outside liberties

[Diagram]
Diag.: No outside liberties

If there are no outside liberties, White can make a sente seki.


[Diagram]
Diag.: Main line

White 1 is the strongest attack. Black 2 is the vital point. Black 6 is necessary or White plays there (or to the right of it) to capture the corner.


[Diagram]
Diag.: Variation at 4

If Black 4 here, White 5 makes a thousand year ko. This result is generally worse for Black than a seki.


[Diagram]
Diag.: Variation at 2

Black 2 at the 2-2 point invites another thousand year ko.


[Diagram]
Diag.: Variation at 2 - White's mistake

White 5 in this variation spoils the chance of a ko and invites a seki.



2. Outside liberties

[Diagram]
Diag.: Outside liberties

If there is at least one outside liberty, Black is alive with 7 points.


[Diagram]
Diag.: Main line

Now Black 2 and the throw in at 4 work. Black 6 creates damezumari for White. If there were no outside liberty, Black 6 would put himself in atari.



Conclusion for the endgame

[Diagram]
Diag.: Outside liberties

White 1 threatens to destroy 7 points in sente (assuming capturing the corner would decide the game). Black 2 makes 7 points in reverse sente. So, White 1 is a typical ko-threat but if so, it is a bad one. In case of a ko the previous diagram supplies 4 ko-threats, that's one more than here.



Path: LifeAndDeath   · Prev: TwoByThreeBox   · Next: WalkieTalkieSeven
This is a copy of the living page "Two by four box" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.