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Eye

 

Two Eyes
  Difficulty: Beginner   Keywords: Life & Death

One of the first things a beginner learns is that a group of stones must have, or must be able to make, two eyes in order to live.

[Diagram]
Diag.: Minimal group with 2 'eyes'

This follows from the basic rules of Go, which state that when a group's last liberty is removed, the group is captured (removed from the board).

It follows that, if a group has at least two liberties which cannot be removed, then the group cannot be killed and is alive.

This is because the opponent stones can't be placed on points that have no open points next to them, (Liberties) - thus neither eyes of a two-eyed group can be occupied, without self capture.

Note that sometimes an 'eye' may have two or more points in it, but that does not neccessarily make the group alive. Each living group needs two separate eyes. Look at Nakade and Life And Death for examples of this.

An eye of 3,4,5,6, or more spaces can be separated into two Eyes, making it alive, depending on the situation. The empty points that separate big eyes into two smaller eyes are vital to the survival of that group and are extremely important to occupy. If occupied by an opponent, the group may be unable to make two eyes. See Vital Point Life And Death

See also:

--MortenPahle (10k) --Edited by Stevertigo



This is a copy of the living page "Two Eyes" at Sensei's Library.
(C) the Authors, published under the OpenContent License V1.0.