Author: Eugene Nalimov
Date: 19:30:27 04/01/04
Go up one level in this thread
On April 01, 2004 at 21:38:22, Marc Bourzutschky wrote: >On April 01, 2004 at 21:30:23, Eugene Nalimov wrote: > >>On April 01, 2004 at 21:15:05, Marc Bourzutschky wrote: >> >>>On April 01, 2004 at 20:36:32, Eugene Nalimov wrote: >>> >>>>On April 01, 2004 at 20:03:20, Marc Bourzutschky wrote: >>>> >>>>>On April 01, 2004 at 17:59:38, Eugene Nalimov wrote: >>>>> >>>>>>On April 01, 2004 at 15:16:34, Marc Bourzutschky wrote: >>>>>> >>>>>>>The Chessmaster format is indeed better >>>>>> >>>>>>What does it mean "better"? :-) >>>>>> >>>>>>It stores less information, thus compresses better. >>>>>> >>>>> >>>>>No, it stores the same information, just in two different files. Those files >>>>>together are still somewhat smaller than the Kadatch compressed ones... >>>> >>>>AFAIK it doesn't stores non-wins for side to move. Is it so? That alone should >>>>result in the better compression. >>>> >>> >>>It stores complete information, just distributed differently. For example, the >>>equivalent of the Nalimov krpkr in FEG is the set of krpkr and krkrp. Each >>>stores only wins for the side to move, but between the two you get the exact >>>same win/loss/draw information. krpkr and krkrp in FEG format togther occupy a >>>little under 127Mb, while the krpkr.nb?.emd files take 150Mb. The complete >>>5-man set in FEG is about 5.6Gb. >> >>Ok, let's assume that position in krpkr is loss for white to move. Where in FEG >>that information is stored? Not in krpkr, because it is not win for side to >>move. Not in krkrp because other side is to move. >> >>What I don't understand? >> > >Yes, the information is stored in krkrp "flipped" with black to move. In the >Nalimov format you don't need krkrp because krpkr stores both wins and losses, >while the FEG format does not need to store losses because they are in krkrp. >In fact, I used the 1-1 correspondence between Nalimov and FEG to trace an e.p. >bug in an earlier version of FEG :-) I see. So in FEG your have krpkr wtm, krpkr btm, krkrp wtm, and krkrp btm. Than yes, you can figure value without the search, at a cost of (probable) extra TB probe. Extra probe is unavoidable when the score is a draw. So your are paying that price, and slower access due to 4x larger block size, to achieve ~30% smaller TBs. Reasonable tradeoff, but I would not call it "better" :-) BTW you can achieve better compression in .emd files by replacing all "broken" scores by the most common non-broken score in the TB. I always was curious how much it will save, but never made the experiment... Thanks, Eugeen >>Thanks, >>Eugene >> >>>>And as was pointed by Gian-Carlo Pascutto FEN format does not allow you to >>>>search in the tree -- i.e. it allows slower decompression. For example, you can >>>>achieve ~10% better compression with Kadatch algorithm just increasing block >>>>size from 8k to 16k. For larger block sizes you can achieve even better >>>>compression using slightly modified algorithm (modifications are useless with >>>>small block sizes). >>>> >>> >>>Yes, the block sizes may be an important factor. FEG uses 32k. How much of the >>>compression advantage would disappear with smaller block sizes only Johan de >>>Koning knows... >>> >>>-Marc >>> >>>>But I believe main reason for better compression is just less information in the >>>>files. >>>> >>>>Thanks, >>>>Eugene >>>> >>>>>-Marc >>>>> >>>>>>Thanks, >>>>>>Eugene >>>>>> >>>>>>>but no interface other than through >>>>>>>Chessmaster is available. Besides, the Nalimov format has become a quasi >>>>>>>industry standard. Since the contents of the two tablebases is the same, the >>>>>>>main advantage of the Chessmaster is faster generation with less RAM, and >>>>>>>somewhat smaller compressed file sizes. If there were a tool to translate >>>>>>>Chessmaster format to Nalimov format we would already have all the 6-man >>>>>>>tablebases by now. >>>>>>> >>>>>>>On April 01, 2004 at 14:18:16, Jason Kent wrote: >>>>>>> >>>>>>>>On April 01, 2004 at 14:07:22, Kurt Utzinger wrote: >>>>>>>> >>>>>>>>>On April 01, 2004 at 13:56:25, Jason Kent wrote: >>>>>>>>> >>>>>>>>>>I just read this in the FEG.txt that i got off the chessmaster website. >>>>>>>>>> >>>>>>>>>>XVI. WHY THE FEG FORMAT? ================================================ >>>>>>>>>> >>>>>>>>>>Perhaps, after reading all of this, you are wondering why Chessmaster >>>>>>>>>>9000 does not use either of the more commonly used EGDB formats, namely >>>>>>>>>>those created by Eugene Nalimov or Ken Thompson (both of which bear the >>>>>>>>>>names of their creators). There are many reasons for this: >>>>>>>>>> >>>>>>>>>>1. FEG data is about 20% smaller. Additionally, half-sets can be used if >>>>>>>>>> hard drive space is an issue, making a "full useable" file set that is >>>>>>>>>> almost 1/3 the size of the complete Nalimov file set. >>>>>>>>>>2. FEG generation is much faster and doesn't need a huge amount of free >>>>>>>>>> RAM to create a set of files. >>>>>>>>>>3. FEG can do any 6-man files on a 32-bit platform. >>>>>>>>>>4. The Thompson format is not a complete set (especially pawns on both >>>>>>>>>> sides are lacking). >>>>>>>>>>5. The Thompson format stores DTC (Distance to Conversion) values, >>>>>>>>>> meaning that it stores the number of moves to either mate OR to a >>>>>>>>>> capture/promotion, and will play whichever move has the smallest >>>>>>>>>> winning value. This can result in silly moves (a capture that leads to >>>>>>>>>> a mate in eight moves instead of a non-capture that leads to mate in >>>>>>>>>> three moves). >>>>>>>>>>6. Since Chessmaster 9000 is a mass market product, the majority of its >>>>>>>>>> users are not aware of these other formats and how to get them. Also >>>>>>>>>> for the ease of development it is easier not to be dependent on >>>>>>>>>> technical support for data that was created using tools that were not >>>>>>>>>> developed by Ubi Soft. >>>>>>>>> >>>>>>>>> Hi Jason >>>>>>>>> Maybe you have asked the wrong question: "Why does Chessmaster 9000 >>>>>>>>> not support the egtb format that all other engines do?". >>>>>>>>> Kurt >>>>>>>> >>>>>>>>The reason I ask is because the egtb format sounds like its a little better. I >>>>>>>>kinda wish cm9k used nalimov so it would be more compatible.
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