# [Computer-go] Liberty races in playouts

Hiroshi Yamashita yss at bd.mbn.or.jp
Sun Apr 26 12:38:00 PDT 2015

```Hi Detlef,

How does your program understand two strings are in capture race?
I tried the detection 100 playouts later, but it did not work well.
http://computer-go.org/pipermail/computer-go/2013-March/005827.html
It could solve some simple semeai, but maybe there are many exceptions.

Aya's semeai knowlege is if string liberty reduce 2 or 3, then try
to kill around 2 or 3 liberty string.
It has some special cases, like

9.XX......    9.XX.O....
8.OXOOXO..    8.OXXXO...
7.OXXXO...    7.OXXXO...
6XOOOXO...    6XOOOXO...
5.XXXOO...    5.XXXOO...
4.........    4.........
3.........    3.........
2.........    2.........
1.........    1.........
ABCDEFGHJ     ABCDEFGHJ

If white(O) play F9(O), Aya think B9(X) string liberty becomes 2
in both cases.

Regards,
Hiroshi Yamashita

----- Original Message -----
From: "Detlef Schmicker" <ds2 at physik.de>
To: "computer-go" <computer-go at computer-go.org>
Sent: Sunday, April 26, 2015 5:07 PM
Subject: [Computer-go] Liberty races in playouts

> Hi,
>
> I wonder which ideas are around for liberty races in playouts.
>
> What nicego does: it reweights the random moves in the playout to make
> sure, that each point is played with roughly the same probability.
>
> This approach tries to solve the problem, that local playout rules
> modify this probability, as this leads to more than one point ending in
> playing at a liberty in a liberty race.
>
> But this just "fixes" the problem that were introduced due to local
> playout rules....
>
>
> What are you doing, and does it work?
>
> Detlef
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> Computer-go at computer-go.org
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```