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Subject: Re: how to detect information about pawn structure based on bitboard

Author: JW de Kort

Date: 01:27:48 12/17/02

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On December 17, 2002 at 03:40:11, Uri Blass wrote:

>I think to add to my program bitboard that will be used only for pawn structure.
>
>2 numbers of 64 bits that are used for white pawns and for black pawns.
>
>I want to detect based on these bitboards a lot of information about every pawn
>and I may want to use the information together with attack tables for
>evaluation.
>
>My question is if using bitboard is a good idea to get the information and
>if the answer is positive how can I detect the information by bitboards
>
>For every pawn I want to detect the following:
>
>1)Is it a weak pawn(a pawn that can never be defended by a pawn and cannot go
>forward to promote without captures and without the risk of being captured by a
>pawn)
>2)Is it probably weak pawn(it means that the only way to defend it by a pawn is
>by capturing the opponent pawn or by letting the opponent to capture the
>potential defender by a pawn).
>
>3)Is it a pawn that is defended by a pawn and if not how many normal pawn moves
>that are not captures and do not let the opponent to capture by a pawn are
>needed to defend it by a pawn.
>
>4)Is it a passed pawn and if it is a passed pawn how many normal pawn moves are
>needed to defend it by a pawn.
>
>5)Is it a potential passed pawn(is the only way of the opponent to stop it is by
>letting the player to have another passed pawn)
>In case that it is a potential passed pawn the question is if it can be done by
>normal means or the only way to make it a passed pawn is by sacrifices
>
>Uri

Dear Uri,

I do this in my 0x88 based program: i use bitboards to do the pawn evaluation.
This evaluation is only on a very basic level but the topics you mention is
covered. I found out that by bitboard it is far easier and quicker to check
whether a pawn is passed or not but i think this is commom knowledge. I found
the source of Crafty very informative.

regards

Jan Willem




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