Computer Chess Club Archives




Subject: Re: Hash Collisions

Author: Robert Hyatt

Date: 07:21:50 02/21/99

Go up one level in this thread

On February 21, 1999 at 01:14:37, KarinsDad wrote:

>I posted this the other day, but it may have been obscured (or not if nobody has
>any information on it).
>I have been wondering if changing the Zobrist hash from a set of random number
>to a set of non-random and very specific numbers could result in a more even
>distribution in the hash table. Has anyone done any work in this area?

Burt Wendroff and Tony Warnock published a paper in the JICCA a few years
ago discussing this.  The main issue is to find the hamming distances between
_all_ the random numbers, and maximize all of them.  Random numbers work fine
if they have been tested (I ran all of mine thru a hamming distance analysis
when I first started).

As far as 'distribution' this is done by the low order N bits
(N=log2(hash_size)) of the hash signature.  You _could_ do the hamming analysis
on just those bits as well.

This page took 0.05 seconds to execute

Last modified: Thu, 07 Jul 11 08:48:38 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.