Author: Uri Blass
Date: 07:46:58 01/10/03
Go up one level in this thread
On January 10, 2003 at 10:19:04, Bas Hamstra wrote:
>On January 10, 2003 at 04:35:17, Uri Blass wrote:
>
>>On January 10, 2003 at 04:05:30, Bas Hamstra wrote:
>>
>>>On January 09, 2003 at 10:18:23, Uri Blass wrote:
>>>
>>>>After I make a move of a white pawn I need to change only part of the bitboard
>>>>of the pawns.
>>>>
>>>>Is there a more efficient way to do it then things like?
>>>>
>>>>if (side==LIGHT)
>>>>{
>>>> pawnattacksAH[LIGHT]=(pawnBB[LIGHT]<<9)&NOTFILEABB;
>>>> pawnattacksHA[LIGHT]=(pawnBB[LIGHT]<<7)&NOTFILEHBB;
>>>>...
>>>>}
>>>>else
>>>>{
>>>> pawnattacksAH[DARK]=(pawnBB[DARK]>>7)&NOTFILEABB;
>>>>...
>>>>}
>>>>
>>>>I remember that GCP told me that I can get the information from hash tables.
>>>>
>>>>Updating pawnBB after every make move that change the pawn structure is cheap so
>>>>I do it but I wonder how can I get the information from hash tables when I do
>>>>not want to use static scores for pawn structure but to use other information in
>>>>the board to evaluate pawn structure.
>>>>
>>>>Should I start with doing it without caring about speed and only later care
>>>>about storing the information that I need in hash tables?
>>>>
>>>>The information that I want first is squares of the passed pawns that are
>>>>protected by pawns and square of the weak pawns of both sides.
>>>>
>>>>There is another information that today I remember without bitboard(number of
>>>>pawns in every file)
>>>>
>>>>Should I change the way that I remember it to bitboard and if yes how to do it?
>>>>
>>>>Uri
>>>
>>>Since you will probably evaluate each pawn anyway, you can keep counters of
>>>pawns at every file. I do that (and I use rotated bitboards). I store an 3
>>>character arrays in my pawnhashtable: WPawnsOnFile[8] BPawnsOnFile[8] and
>>>KingSafety[8]. If white castled short and black long, KingSafety[1] will give me
>>>white's kingsafety and KingSafety[6] gives black's KingSafety.
>>>
>>>Bas.
>>
>>I do not understand what does king safety in your pawn hash tables.
>>
>>I also do not understand your example
>>KingSafety[1] is for the king in g1 so my first thought is that it is relevant
>>for the g file.
>>If I assume that h file is 0 and g file is 1 then in this case c file is 5 and
>>not 6.
>
>It works like this: You calculate the weaknesses in the f-g-h pawns for white,
>as if white had castled short. Than you do the same for the a-b-c pawns for
>white, as if it castled long. Both scores are stored in the pawnhashtable. Now
>if later on the white king castled short (or long, it doesn't matter), I can
>lookup the the score for the "castling formations" in the pawnhashtable. To make
>this a little more advanced I also take into account the scores in case of
>"opposite castling", since pawnstorms are more important there. In my case this
>results in 8 KingSafety scores, 4 for white and 4 for black that are calculated
>once and "looked up" many times.
>
>Remember, the score reflects not only the structure of the 3 pawns in front of
>the king, but also how many (half-) open files there are on the king, is there a
>pawn storm going on, how far have I pushed my qeenside pawns if black castled
>long etc.
>
>
>Best regards,
>Bas.
Thanks but I still do not understand.
The scores that you store for king safety are evaluation or information about
pawn structure?
If it is evaluation then I do not like it because the score for king safety that
I still do not have may be dpendent on other things and not only on pawn
structure and the same pawn structure that is a problem in one case may be not a
problem in another case.
If it is information that is used for evaluation then I do not understand
what information.
Uri
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