Author: Robert Hyatt
Date: 07:11:32 07/30/04
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On July 30, 2004 at 06:23:37, Gerd Isenberg wrote: >On July 29, 2004 at 16:32:11, Robert Hyatt wrote: > >>On July 29, 2004 at 14:09:13, Gian-Carlo Pascutto wrote: >> >>>On July 29, 2004 at 14:07:10, Robert Hyatt wrote: >>> >>>>On July 29, 2004 at 06:26:52, Gian-Carlo Pascutto wrote: >>>> >>>>>http://arxiv.org/ftp/cs/papers/0406/0406038.pdf >>>>> >>>>>I stumbled onto this when doing a search for Axon. >>>>>Not seen it mentioned here yet. >>>>> >>>>>They also have a paper about hashing out which I can't >>>>>download. >>>>> >>>>>-- >>>>>GCP >>>> >>>> >>>>Doesn't strike me as particularly interesting. IE it almost seems that they >>>>don't realize that most programs store positions in a repetition list as 64 bit >>>>Zobrist integers... >>> >>>Look at the hasing paper abstract, do some quick math, and you'll see they >>>apparently don't know or don't use 64 bit hashing ;-) >>> >>>-- >>>GCP >> >>I know. If this was published, I wonder where the referees were? ;) > > >I found the algorithm rather smart. A few aspects: > >1. They mention hash keys or part of hash keys at page 4/5. > >2. They don't need hashkeys in game history as well in current searched move >string as well. Only 16-bit moves. > >3. The algorithm only needs a local concatination list of 25 16-bit words and is >therefore much more memory friendly. > >4. They don't have any problems with rare collisions, where the zobrist xor-sum >of 2*N reversible moves is zero, but without a repetition. > > >I use the idea of Ronald de Man as a precondition for a possible repetition, a >small hashtable (2**12..14 bytes) indexed by some bits of the zobrist hashkey, >see Van Kervinck's thesis: > >http://brick.bitpit.net/~marcelk/2002/marcelk-thesis.pdf >2.7 Implementation delails page 39. > >Gerd Bruce Moreland used a similar idea. I played with it for a while but for a parallel search it introduces a new problem, namely that each search needs an independent repetition mechanism so there is no interaction between the two or more searches. The list seems easiest.
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