Door group

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  Difficulty: Beginner   Keywords: Life & Death, Proverb
[Diagram]

The door group

The black shape in this diagram is called the door group, and it is dead as it stands.

[Diagram]

Attempt to live

Creating some sort of shape by turning at B1 is Black's strongest attempt to live. White refutes it by reducing Black's eye shape with W2. After that, a and b are miai to limit Black to one eye.

[Diagram]

One leg

The door group with one extra leg is unsettled. Since a move at a reduces the shape to the dead door group, it is White's killing move. Incidentally it is also one of the moves allowing Black to live. From this it is also easy to understand that the door group with two legs is unconditionally alive.

[Diagram]

Derived shapes

The presence of hane at the marked points helps a bit towards life for the black group, while absence of either black+circle stone helps a lot towards its death. Keeping this in mind, together with the shapes above, will help you to analyse similar situations in your games.


--Stefan


Exercises on the door group:


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This is a copy of the living page "Door group" at Sensei's Library.
(OC) 2009 the Authors, published under the OpenContent License V1.0.
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