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Subject: Re: Evaluation function question

Author: Peter McKenzie

Date: 17:49:07 06/17/02

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On June 17, 2002 at 20:01:39, Russell Reagan wrote:

>I'd like to know how many people have to add in a lot of special case code to
>their evaluation function(s). For example, does your king safety code in your
>evaluation function make your program want to castle, or do you have to add in
>code that penalizes the program if it hasn't castled? I suppose I'm wanting to
>know how many people have a "natural" evaluation function that takes care of
>these kinds of special cases without those cases having to have an extra "work
>around" to work.
>
>Secondly, do you think either approach is superior to the other? I think the
>"natural" method would seem to be better. For example, if you reach an endgame
>and castling still happened to be legal, and your program castles to get rid of
>the "non-castling" penalty, even though your king should be trying to get
>centrally located in the middle of the board. If your program had "king safety"
>factors instead of the castling work around, then it wouldn't castle and would
>play a more correct move. Seems pretty straight forward to me, but I've been
>wrong before.
>
>Other examples could be using a piece-square table with low values for the
>border squares and high values for the central squares so that the program
>"controls the center" in the opening. Or penalizing pieces that haven't moved
>yet in the opening, or penalizing pieces that have moved more than once, etc.
>These seem to be very poor methods of approaching an evaluation function at
>first thought, but I haven't worked extensively on my own yet, so I'm no expert
>here.
>
>I'd like to know your thoughts...

I have some special case code, but not for castling.
Castling is handled well enough by things like penalising a centralised king
when there is plenty of material on the board, and by giving bonuses for rooks n
open files etc.

>
>Russell



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