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Subject: Re: fixed depth evaluation problem

Author: Uri Blass

Date: 12:14:18 06/16/02

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On June 16, 2002 at 14:12:15, Stan Arts wrote:

>Hello,
>
>I´m working on my chessprogram, it´s very new and I have just gotten a
>simple method of alpha-beta working in my program. Other than that it is
>still a simple fixed level mini-maxing program at the basis.
>
>Now my question, when it was still doing a full width scan, my program would
>usually only see 4 ply deep, 5 if you had a lot of patience. However, the
>evaluationfunction would cause it to play like it should more or less, I
>mean the positional parameters I put in it, but now with alpha beta, it
>can usually search 6 to 7 ply deep, but now it tends to see strange deep
>threats causing it to play strange countering moves, instead of really
>listening to the evaluation parameters like with lower plies. For instance,
>it basicly throws open it´s king side pawns when in the evaluationfunction
>it says it shouldn´t :) Still, when I limit play to 4 ply even with alpha
>beta it plays as before, so I know the alpha beta works right.
>Another problem is for instance that it won´t castle, because it keeps
>"fishing" for other opportunity´s on deeper ply´s instead, instead of just
>setling for the castling bonus, constantly delaying a good move by making
>the opponent counter something. This is strange, and on these bigger plies
>it constantly wants to do this. Always thinking "i can castle later" for
>instance.
>
>Would this problem only be solvable by extensions? Or can it be solvable
>by increasing scores in the evaluation, because I think that when I increase
>penalty scores, it becomes dangerous in the way that it then would start
>sacrificing to achieve something which isn´t worth that much. = dumb
>Anyone ran into this similair problem with their fixed level program?
>
>Please help out a starting (21 year old) chess programmer,
>
>Thanks!
>
>
>Stan


I do not know.
I also think that you have some bug because I never had an experience like this.

Uri



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