# [Computer-go] living by two false eyes

fastgo fastgo at gmail.com
Wed Apr 6 07:48:10 PDT 2011

```Generally, game status update performs life and death check. But it is too
slow for playout. So it is turned off at the early stage of the playout.When
the game length reached a certain number for example 63 moves on 9x9, it
started to perform unconditional life and death check.

Once a region is identified as unconditional eye, the move is forbidden from
either side.

It is true that as you pointed out, it may be too late sometimes. But as
long as it gets right with a decent probability, the RAVE will pick it up.
On the tree level, the RAVE will detect the eye point is critical after a
good number of playouts.

On Wed, Apr 6, 2011 at 10:33 AM, Brian Sheppard <sheppardco at aol.com> wrote:

>  The Benson algorithm is used to detect unconditional life. It should
> identify these strings as alive, which is good. I think that most of the
> problem with the two false eyes is that their owner might incorrectly fill
> one of them before reaching a late game stage, so perhaps that does not
> solve the problem.
>
>
>
> Can you tell me how the Benson algorithm is used in StoneGrid?
>
>
>
> Thanks,
>
> Brian
>
>
>
> *From:* computer-go-bounces at dvandva.org [mailto:
> computer-go-bounces at dvandva.org] *On Behalf Of *fastgo
> *Sent:* Wednesday, April 06, 2011 10:11 AM
> *To:* Aja; computer-go at dvandva.org
>
> *Subject:* Re: [Computer-go] living by two false eyes
>
>
>
> In StoneGrid, it has built in the Benson algorithm in the playout. It does
> not seem to help much on overall strength. But I think it should solve the
> case here.
>
>
> I think you can implement the Benson Algorithm in the late stage of the
> playout.
>
> It has another advantage finishing the playout in shorter length. In
> StoneGrid, the playout on average finishes in a little bit more than 70
> stones on 9x9.
>
> You need quite a lot of effort to get it fast as well as correct. So the
> return of the effort is low.
>
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