[computer-go] The physics of Go playing strength.

[Łukasz Lew]

Libego played at old CGOS with name sth like UCT-107-???k

100k was about 1550k
200k about 1650k

I don't remember and I can't find the rating list anymore.

Łukasz

On 4/14/07, Darren Cook <darren at dcook.org> wrote:
> >> I've been trying the libego program "out of the box", and am up to
> >> 200,000 UCT playouts, but still gnugo 3.6 on level 6 is winning 10 out
> >> of 10. ...
> >
> > If 200,000 play-outs is being beat, something is broken.  Even
> > a bad implementation should do better than that.
> >
> > Does libego provide a full UCT implementation out of the box?
>
> Thanks for the reply Don.
>
> I've just reviewed the code again and it seems to be the same algorithm
> as described at http://senseis.xmp.net/?UCT
>
> The way it is implemented differs from the pseudo-code in a few minor
> ways, but notably: it (libego) maintains a float win-rate for the node,
> which is updated, rather than storing wins and recalculating win-rate
> each time. I suppose there could be a rounding error creeping in there.
>
> I've tried changing it to use two ints, for total visits and black wins,
> and then calculate the winning rate on the fly. But it still cannot win
> a game against gnugo on level 6: it lost 9 out of 9 at 100K playouts,
> and has lost 4 out of 4 at 500K playouts. Yet there is no major bug:
> when I played it a game at each of 100K and 500K it played reasonable
> go, and I could notice that 500K was stronger.
>
> Has anyone else tried studying or using libego's UCT implementation? Is
> there another open source implementation of UCT I can compare against?
>
> > One thing that I think most people are doing is related to how you
> > select a move once you have finished the search.   Do you pick the
> > highest scoring move? ...
>
> No, currently it chooses the most visited node, ignoring score.
>
> Darren
>
>
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