Blind eye

  Difficulty: Intermediate   Keywords: Life & Death, Theory

A blind eye of a chain C is a term proposed by Patrick Traill for use in the context of Benson's Definition of Unconditional Life for an enclosed region that fails to be vital for C (an eye of C) because not all vacant points in it are adjacent to the C.

Benson's theorem states that a set S of chains is pass-alive (cannot be capture by the opponent however many moves in a row he has) if and only if each chain in S has two eyes enclosed by S; an eye of a chain is a maximal connected collection of empty points and opposing stones such that every vacant point (and, if suicide is allowed, every opposing stone) in it is adjacent to C.


Blind eyes

For the chains marked black+cross:

f marks a false eye that is not blind

g is false and blind

b marks a blind eye

r marks a real eye

See also

Blind eye last edited by PJTraill on September 9, 2018 - 22:43
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