2x2 board

    Keywords: Theory

A 2x2 Go Board:

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2x2 board


See also: Positions and Games on 2x2


Example games

[Diagram]

2x2 board

[Diagram]

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White 4 captures two stones

prisoners: black+circle black+circle

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prisoners: black+circle black+circle

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White 6 captures 1 stone

prisoners: black+circle black+circle black+circle

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Black 7 captures 3 stones

prisoners: black+circle black+circle black+circle white+circle white+circle white+circle

There are some who would object to this move under superko rules.

Bill: Is there any rule set currently in use that has a superko rule that allows B7?

[Diagram]

score: White wins by komi value

prisoners: black+circle black+circle black+circle white+circle white+circle white+circle


Tas: How about:

[Diagram]

prisoners: black+circle black+circle

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White 6 captures 1 stone

prisoners: black+circle black+circle black+circle

[Diagram]

Black 7 captures 3 stones

prisoners: black+circle black+circle black+circle white+circle white+circle white+circle

No superko problems now.

[Diagram]

back to start

prisoners: black+circle black+circle black+circle white+circle white+circle white+circle

This can go on four times before stopped by superko, but neither player gains. Can a player cleverly use superko to his advantage?

[Diagram]

game ends

Assuming the superko rule it's possible for black to end the game here. The position is seki.

Tas: But no advantage...

impu1se: Presumably black wins with area scoring.


Bill Taylor proved that under area scoring the perfect play score is 1. The proof consists of two parts: 1) Black wins by at least 1 point. 2) Black wins by at most 1 point.


[ext] John Tromp's partial SGF file


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(OC) 2014 the Authors, published under the OpenContent License V1.0.
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