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Subject: Re: The Relation between Search and chess-style

Author: Gian-Carlo Pascutto

Date: 03:27:59 12/15/05

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On December 15, 2005 at 02:35:39, Chrilly Donninger wrote:

>Its obvious that the evaluation influences the style of a programm. But
>interestingly the shape of the search tree has also a significant influence. As
>a rule of thumb: The programm prefers lines with larger (sub-)trees. If one
>increases a certain extension the chances for such moves to be played increases
>(to opposite holds for pruning).

I would say it depends on whether one is winning or losing (score rising or
dropping). When one is winning, the longer lines (extended ones) have generally
better scores, so they get preference.

When one is losing, the preference is for the shorter lines (the pruned ones).

This effect is the opposite of what the programmer wants.

>I am certain, that this effect exists, but I do not exactly know the reason. One
>explanation is: The evaluation consists of a true term which properly reflects
>the value of the position and white noise. If the programm has many choices,
>because the search tree is large, the expected value of the white noise is
>higher.

Correct is: the expected extreme values are higher.

>For non statisticans: If one picks from a bag with 1000 numbers randomly
>1 number and the next time 10 numbers, the chances are very high, that the
>maximum of the 10 numbers is greater than the number picked first.

It also applies to the minimum (see above), so I don't think this explanation is
all of it.

--
GCP



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