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Subject: Re: how much does eval effect strength?

Author: Michael Yee

Date: 05:45:28 09/18/03

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[snip]

>I did an experiment once... I made a version of GLC 2.18 that used only material
>balance in its evaluation.
>
>It played a 20 game match against GLC 2.13.  During the match 2.18 averaged 2 to
>4 ply more than 2.13 (mainly due to extra cut-offs, the NPS search speed was
>only about 20% faster).
>
>The result... 2.13 won, by 19.5 points to 0.5 points.  This gives roughly a 640
>ELO rating difference.
>
>Normally I would expect 2.18 to be about 50 ELO stronger than 2.13.
>
>So loosing the 'positional' part of the eval function seems to have caused
>around a 700 ELO drop in strength.
>
>Conclusion: the evaluation is important.  :)
>

[snip]

Very interesting experiment! The result isn't exactly what de la Maza predicted
in his "400 Points in 400 Days" article on ChessCafe:

   You can refine this experiment further by creating two personalities,
   one that can see three moves ahead but has no positional knowledge and
   the other that can see two moves ahead and has complete positional
   knowledge. The tactical personality, which can see three moves ahead,
   will win the vast majority of the games.

   [http://www.chesscafe.com/text/skittles148.pdf]

I wonder how much of the 700 ELO points gained in GLC due to positional
knowledge came from pawn structure, king safety, mobility, etc...

Michael



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