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Subject: Re: How do you insure that Hash Table entries are correct?

Author: Larry Griffiths

Date: 23:42:10 09/16/00

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On September 16, 2000 at 17:04:23, Dan Newman wrote:

>
>I once tried to measure the error rate and got no errors at all with 64-bit
>hashcodes over several hours of testing.  I was able to measure the error rate
>for 32-bit hashcodes--that was about 1 false match/second (at perhaps 100k
>probes/s).  I think someone came up with an estimate of (very approximantely)
>one error/day with a 64-bit hashcode at 100 knps--or was it 1 Mnps?  Anyway,
>the error rate is very low and can mostly be ignored.  I do try to make sure
>that such an error won't crash my program though...
>
>-Dan.

I dont know what is happening but I ran 78 positions from BWTC suite
and got over 10,000 mis-matches using my 64-bit hash keys.
I looked at my smallboards and they usually differ by a piece missing or in a
different position.  My Piece table does not have zero or duplicate entries
and the random numbers in the piece table look good.
I built hashkeys using the two different smallboards and they do indeed
generate the same hashkeys.

Maybe my hashkeys should be prime numbers?

Larry.



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