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Subject: Re: programmers: pawn hash tables

Author: Uri Blass

Date: 01:03:50 03/08/03

Go up one level in this thread


On March 08, 2003 at 03:43:20, Ed Schröder wrote:

>On March 08, 2003 at 01:42:15, Robert Hyatt wrote:
>
>>On March 08, 2003 at 01:29:46, Joel wrote:
>>
>>>Hey All,
>>>
>>>Just wondering what everyone thinks is the best way to implement a pawn hash
>>>table?
>>>
>>>At the moment I am incrementally generating a seperate pair of pawn hash keys,
>>>and using them to index a table - very similar to how my transposition table
>>>works.
>>>
>>>Is it possible to do _significantly_ better than this? It seems to be somewhat
>>>expensive to do, although having said that my NPS still went up at least 20% in
>>>most situations.
>
>>That is what everyone since chess 4.x has done.  Two signatures, one for
>>all pieces and pawns, one just for pawns.
>
>I don't use it, the problem is that you can not evaluate the coherence between
>pawns and the other pieces. If you have stuff like that in your eval pawn
>hashing is unusable and IMO that evaluation (coherence) is a must in a chess
>program.
>
>My best,
>
>Ed

1)You can use hash for pawn structure not to remember evaluation but to be able
to calculate faster the squares of passed pawns or isolated pawns.

2)I believe that the main must in chess program after basic evaluation is
searching deeper.
I believe that 1 ply can give more than evaluating coherence between pawns and
the other pieces.

Uri



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