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Subject: Re: Automatic Eval Tuning

Author: Steve Maughan

Date: 09:23:16 06/29/01

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Vincent,

>The bigger your evaluation is, the more problematic tuning it automatic
>is.

True - as the domain space increases it is more difficult to find the optimal.

>Also automatic tuners don't have any chess knowledge, so they
>don't see the difference between tuning passed pawns negative if you happen
>to have a testset where a passer is bad now and then.

You simply need a large test set.  This is the same problem as solving a set of
equations.  In that case you have 'x' unknowns you need 'x' equations.  In the
case of an evaluation function you will need much more due to interaction.

>Another problem for automatic tuners is that you tune for testposition set X,
>but that in reality it has to work well also for testset Y where it has
>not been tuned for.

Again you need a large test set.

>Evaluations hand tuned take into account testset Y, not only testset X.

Not necessarily.

>Anyway, when your number of parameters gets quite a big number then
>automatic tuning doesn't work anyway anymore.

It is certainly more difficult.

>Of course it might beat random chosen parameters, but it'll never beat
>hand chosen parameters (unless a fool choses them).

This is not the case for some other games.  Othello being an example.  ALL
decent Othello programs (e.g. mine www.maughan.clara.net) are automatically
tuned.  Othello is a purely positional game and lends itself to self tuning.
Chess is MUCH more complex but I predict that in the next ten years we will see
some significant advances in automatic evaluation tuning.

Regards,

Steve Maughan




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