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EyesCollection

Referenced by
GoTerms
TwoEyes
TwoHeadedDragon
NoEyeVersusNoEyeC...
GeneralEyeDefinition
EyeDefinitionDisc...
TwistedFour
CornersThenSidesT...
BasicStrategyOfGo
EquivalentGameToGo

 

Alive
Path: EyesCollection   · Prev: TableOfEyespaces   · Next: Dead
  Difficulty: Beginner   Keywords: Life & Death, Go term

A group is alive when it can't be captured.[1]

There are several ways in which a group can 'live'. The most common are:

  • the group is secure enough to survive an invasion[2].
  • the group has two eyes
  • the group lives in seki.

[1] That is, the group as a whole isn't one the opponent can forcibly capture. Stones within it may be captured.

[2] A group that does not obviously have two eyes, or is not clearly in seki, is still alive if it is guaranteed to be able to get two eyes or make seki, regardless of who plays first. By this extended definition, groups that seem to be alive, or are alive can die if a player is negligent.


Jasonred : Or against people who either don't know about seki or didn't notice seki, or have the seki used as a ko threat... it is not necessarily unconditionally alive. A (non corner?) group with two eyes is more or less indestructible, come what may.

Charles No, unconditional life is a quite different theoretical concept. The usage on that page is also non-standard. Live groups often die.


Being alive is one possible status of a group, as is being dead; in between groups are called unsettled, or in more open positions weak groups.


Tactics for making live groups can even combine threats: to make an eye, or to connect.

[Diagram]
Diag.: Two white groups are alive

In this example the right-hand white group is alive, with two completely explicit eyes. The left-hand white group is also alive.


[Diagram]
Diag.: Black cuts, White makes a second eye

White can answer Black 1 with White 2 for two eyes.


[Diagram]
Diag.: Black makes the eye false, White connects

Black 1 here makes a false eye shape, but once White plays 2 all white's stones form one safe, live group.



See also the Eyes Collection and Benson's Algorithm (so-called unconditional life).



Path: EyesCollection   · Prev: TableOfEyespaces   · Next: Dead
This is a copy of the living page "Alive" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.