[Welcome to Sensei's Library!]

StartingPoints
ReferenceSection
About


Referenced by
TwoByThreeBox
LibraryLobby

 

Two by three box - discussion
    Keywords: Life & Death

[Diagram]
White 2 kills

I thought I was Captain Smooth by making my little 2x3 box, but I didn't recognize the death that lay waiting with W2. D'oh!

Why does it kill?

[Diagram]
Why White 2 kills

At this point, the best Black can do is to trap three in a row, which is dead. For the most part, once you've lost both 2-2 points, you're dead in the corner.

-- Scartol

Both 2-2 points? ummm...



Note that this only works because of shortage of liberties that occurs in the corner. On the side, or in the middle this is alive as it is:

[Diagram]
Black has one extra liberty

"Captain, it's alive!" -



[Diagram]
White creates a ko



RMDow?: The same is true for 2x3 in the corner with two or more external liberties (Black is alive). When there is exactly one liberty, the best White can do is to play a ko to create bent four in the corner Dieter: I disagree: White makes a two-stage ko. There is no 'bent four in the corner' (in the sense that it is dead by the rules). This a just a ko, fully played out.


[Diagram]
Black is dead

unkx80: I have added this in response of a query in Kanazawa Solution 24, and I think it is appopriate to post it here.

In this diagram, Black is dead.

No, this is not a seki. Why?


[Diagram]
Explanation 1

After W1 and W3 fill up all the external liberties, the BC stones are caught in a connect-and-die.


[Diagram]
Explanation 2

If B1 prevents the connect-and-die at any point of the game, he turns his group into a straight three big eye instead and dies in gote.



This is a copy of the living page "Two by three box - discussion" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.