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Subject: Re: Hashkey collisions (typical numbers)

Author: Vincent Diepeveen

Date: 06:18:05 04/07/04

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On April 07, 2004 at 08:56:26, James Swafford wrote:

>On April 07, 2004 at 06:55:31, Andrew Williams wrote:
>
>>On April 07, 2004 at 06:49:59, Renze Steenhuisen wrote:
>>
>>>
>>>Hi all,
>>>
>>>could someone give me some numbers that are common with hashkey collisions?
>>>Because I guess my % is little too high...
>>>
>>>I'm getting like 0.03% [which is 1 every 3000, if I'm not mistaken]
>>>
>>>This is when using TT=32MB (haven't got the exact number of entries)
>>>
>>>If you think it is an error, any suggestions on where to start looking?
>>>
>>>Thanks!
>>>
>>>   Renze
>>
>>One in 3000 seems very high. How many bits are there in your hashkey?
>>
>>Andrew
>
>
>Even though you said you're using Crafty's random num gen,
>I would start by doing some hamming-distance checks.

Not needed at all. It's a fine algorithm implemented in crafty by Gijsbert
Wiesenecker (adapting his ZZZZZZ code).

It will be some simple bugs by Renze.

>For reference, my program gets:
>Checking minimum hamming distance between random keys: 14 bits
>Checking average hamming distance between random keys: 31 bits
>
>If your hamming distances are comparable, you can conclude
>your zobrist keys are ok, and go from there.
>
>--
>James



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