Author: Robert Hyatt
Date: 15:02:17 12/23/00
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On December 22, 2000 at 15:12:52, Ernst A. Heinz wrote: >Hi Peter, > >>These are meant to be permanently stored in RAM, and thus the significant RAM >>requirement. At the same time Nimzo8 still uses Nalimov tablebases and assigns >>RAM for that. >> >>1. Isn't there an overhead of trying to use both? >>2. What is a reasonable strategy for allowing Nizmo8 to use one vs. the other? >>I.e. should a nominal amount of RAM be assigned for caching Nalimov tablebases >>and the rest (as much as possible) to Nimzo's own? >>3. Finally, does it make sense to increase these allocations at the expense of >>the main hash table size? > >Chrilly Donninger's RAM-based endgame databases are based on a >technique first used in our chess program "DarkThought" during >the 15th WMCC in 1997. I named them "knowledgeable endgame >databases" because they employ domain-specific a-priori knowledge >to reduce the amount of information stored per position to just >a _single_ bit in many cases. This is only half the space that >would be required for vanilla W/D/L = win/draw/loss databases >using 2 bits for the three W/D/L values per position. > >The RAM-Based knowledgeable endgame databses of "DarkThought" >consume less than 16MB of RAM for the full set of all 3- and >4-piece endgames. AFAIK, Chrilly has added some more databases >while compressing them on top of the knowledgeable encoding >scheme with a standard compression technique. > >According to my own experiences with "DarkThought", RAM-based >knowledgeable endgame databases are certainly worthwhile every >bit of RAM they consume. Hence, I always load them if possible. > >Please point your browser to the WWW pages of "DarkThought" at >http://supertech.lcs.mit.edu/~heinz/dt/ to find out more about >our RAM-based knowledgeable endgame databases. > >=Ernst= The problem hits on the 5 piece files. 7.5 gigabytes reduced to one bit (win/not-win) is still a gigabyte. That's too big for memory, unless I am running on a Cray. Or a PC with a couple of gigs of RAM (which is doable).
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