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Subject: Re: Pawn hashing without Zobrist keys

Author: Omid David Tabibi

Date: 14:09:42 09/12/03

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On September 12, 2003 at 17:00:25, Gian-Carlo Pascutto wrote:

>On September 12, 2003 at 16:53:44, Omid David Tabibi wrote:
>
>>assuming 'table_size' is a power of 2, the following two expressions are
>>equivalent:
>>
>>address = key % table_size;
>>address = key & (table_size - 1);
>
>That's exactly the problem. He generates his hashkeys by
>taking the differnce of the white and black pawn bitboard.
>
>If you 'AND' off a piece of that, you're just cutting out a part
>of your board - with massive hash collisions as a result.

Why use bitboards to generate hash keys then, when you have such a simple and
fast implementation with zobrist keys?


>
>You want something more nonlinear.

You want something more simple. In most cases simplicity also means speed :)


>
>--
>GCP



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