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Subject: Re: Hashtables: is larger always better?

Author: Robert Hyatt

Date: 11:56:02 09/26/01

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On September 26, 2001 at 14:40:53, Gian-Carlo Pascutto wrote:

>On September 26, 2001 at 13:05:43, Robert Hyatt wrote:
>
>>I really don't want to test with smaller keys.  When I tried 32 bits in the
>>tests Stanback, I and others did, it was horrible.  Collisions per second.  I
>>didn't think the search could stand that.  However, I have never tried to
>>determine how many collisions (replace this with bogus scores) the search can
>>tolerate with no ill side-effects.  That would be a _very_ good paper.  Which I
>>suppose I will write if nobody else does...
>
>For some anecdotal data:
>
>Sjeng has been using 32-bits for normal chess for quite some time
>and I don't seem to crash & burn (*). Didn't seem to change much going
>from the cyrix120 to the Athlon 1000 either.
>
>However! If I use a large openings book and do not disable probing
>it after the opening I _have_ gotten collisions and several times
>so! (and unfortunately in that case a _single_ collision will absolutely
>kill you)
>
>(*) I discovered recently that in about 5-15% of the cases I was
>getting bogus evaluations back in crazyhouse chess due to a hashing
>error. It _was_ producing bogus scores in the search, but 'fixing'
>it doesn't seem to have affected the strength of my program. Amazing
>isn't it?
>
>--
>GCP


The last thing is interesting.  Still has my curiousity up to see just how
many "errors" are required before the search falls apart.



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