[computer-go] MC approach

[Nick Apperson]

If it only did one playout you would be right, but imagine the following
cases:

case 1: White wins by .5 x 100, Black wins by .5 x 100
case 2: White wins by 100.5 x 91, Black wins by .5 x 109

the method that takes into account score would prefer the second case even
though it has a lower winning percentage that may be represented by the fact
that white is making an overplay for instance.  Obviously this is just one
example, but there are many cases like this and overplays tend to be
priveledged in a sense I would suspect with this kind of algorithm.

- Nick

On 2/7/07, Matt Gokey <mgokey at charter.net> wrote:
>
> Don Dailey wrote:
>
> > On Wed, 2007-02-07 at 11:34 +0100, Heikki Levanto wrote:
> >
> >>All this could be avoided by a simple rule: Instead of using +1 and -1
> >>as the results, use +1000 and -1000, and add the final score to this.
> >
> >
> > Heikki,
> >
> > I've tried ideas such as this in the past and it's quite
> > frustrating - everything that tries to take territory
> > scoring into account weakens the program.
> >
> > If you just need to see prettier moves,  I think it is
> > good enough to priortize the moves using some other
> > algorithm at the root of the tree.   If you just cover
> > the case where a program is "easily winning" or losing
> > it will play "nicer" but not stronger.
>
> Don, do you have any theories or information about why this is the case?
>
> I would think either way the algorithm should always prefer higher
> average win probabilities, but faced with alternatives where the win
> probabilities are same or nearly the same but the average winning
> margins are higher for one alternative, wouldn't it be better to take
> the path with the better margin? I mean it may in fact be wrong about
> the win/loss classifications so choosing the better scores would seem to
> make sense within reason as long as it's not greedy.
>
>
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