Author: Uri Blass
Date: 01:46:16 12/17/02
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On December 17, 2002 at 04:27:48, JW de Kort wrote: >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 1)This seems to be not very basic level. In the match steve ham against computers Nimzo7.32 could not evaluate correctly a black passed pawn at c3 that could not be protected by a pawn and gave it a big bonus. If even Nimzo7.32(that is at the level of the top amateurs) could not evaluate it then it means that it is not a basic evaluation because I expect nimzo7.32 to know at least everything that is very basic level. I guess that big majority of the chess programs do not have this information because most amateurs have less knowledge than nimzo7.32(movei of today even does not evaluate passed pawns). 2)Where did you look at crafty source code to find the relevant information that helped you? Note that I plan to use the information for the evaluation but it does not mean that this information will give me the evaluation because I want to evaluate weak pawn that is attacked by the opponent as less than weak pawn that is not attacked by the opponent so I may use my attack tables. 3)What is the level of your program? Uri
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