Author: Andrew Dados
Date: 12:38:49 09/26/01
Go up one level in this thread
On September 26, 2001 at 14:56:02, Robert Hyatt wrote: >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. Two loose remarks here: - Assuming about equal distributions of fh and fl scores in HT, single error will be 'no error' in 50% of times. - False fl or fh causing score backed up to root will result in research with different bounds which will quite likely weed out hash entries with not adequate bounds. So maybe simply counting hash entries with 'inadequate bounds' on research can give some insight into how many nodes in total are 'lethal nodes' changing score with hash hit only. -Andrew-
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