Author: Robert Hyatt
Date: 18:53:57 12/21/00
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On December 21, 2000 at 13:33:35, Peter Kasinski wrote: >On December 21, 2000 at 10:18:26, Robert Hyatt wrote: > >>On December 21, 2000 at 09:45:23, Peter Kasinski wrote: >> >>>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? >>> >>>If someone has info/interesting experiences with the above, please do share >>>:)Thanks! >>> >>>PK >>> >>>ps. Merry Christmas to all (who celebrate)! >> >> >>The Nimzo tablebases are win/lose/draw, which makes them much smaller than the >>normal distance-to-mate tablebases. They are used only in the search as they >>can't tell which move leads to the shortest mate. Once the root position is >>5 pieces, normal tablebases have to be used to avoid repetitions, which is why >>both are needed. > >Thanks, I was wondering about their size too. >But what do you think Bob of the trade-off between using RAM for the main hash >tables and tablebase caching? > >PK I don't do that, so I can't really say. The issue is that the full set of 3-4-5 piece files take 7.5 gigabytes. The win/lose/draw files should take 3/256 of that amount, or roughly 88 megabytes. That is a lot of memory to dedicate to the endings, but it might be worth it as there would be _no_ disk accesses inside the search. I am afraid that 88 might be a bit low, as the win/lose/draw tables might not compress as well as the full 8-bit tables. I would guess that 200 megabytes might be a reasonable guestimate... As far as EGTBs vs RAM, yes you get hurt in the middlegame, and make it up in the endgame. You might even try demand=loading the files you need as you encounter each endgame class for the first time, so that this isn't a big problem...
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