Re: [computer-go] What is the eye?

[Erik van der Werf <E.vanderWerf@xxxxxxxxxxxxx>]

Tapani Raiko wrote:
> > What is eye? and How do you define it?
>
> It could be defined as "sufficiently small" region completely surrounded
> by a single string of stones (and the edge of the board).
 _ _ _
|. # #
|# . #
|# #

???

Maybe something like the part for defining single-point eyes in the 
Migos rules is what you are looking for:

----
A connector is an intersection of a region which has at least two 
adjacent intersections that are part of that region.
A unique connector is a connector that would split the region in two or 
more disconnected regions if it would be removed from the region.

A single-point eye is an empty intersection which is
- not a unique connector, and
- not adjacent to any other empty intersection, and
- adjacent to stones of only one colour.
----

For larger eyes things get a bit more tricky. Maybe focus on fully 
accessible regions (regions where a strategy can be proven to become 
adjacent to all empty intersection).

Erik


> In a strict
> sense, sufficiently small means that a black eye can contain only white
> stones and all the empty points inside must be liberties for black. In a
> loose sense, white should not be able to fit a living group inside.
>
> Instead of trying to define an eye and requiring a group to have two of
> them to live, I recommend Benson's algorithm instead:
> http://www.cs.ualberta.ca/~games/go/seminar/notes/020717/benson.pdf
> Definition of a single eye might still be useful in semeai and so on.
>
> --
>  Tapani Raiko, <tapani.raiko@xxxxxxxxxxxxxxxxx>, +358 50 5225750,
>  http://www.hut.fi/u/praiko/
>
>
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