Author: Marc Bourzutschky
Date: 20:04:33 04/01/04
Go up one level in this thread
On April 01, 2004 at 22:30:27, Eugene Nalimov wrote: >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" >:-) > Well, it is also "better" in the sense that it left space for header information in the files :-) -Marc >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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