Author: Uri Blass
Date: 16:32:36 04/02/04
Go up one level in this thread
On April 02, 2004 at 19:14:22, Vincent Diepeveen wrote: >On April 02, 2004 at 18:36:56, Uri Blass wrote: > >>On April 02, 2004 at 18:17:23, Uri Blass wrote: >> >>>On April 02, 2004 at 17:56:58, Robert Hyatt wrote: >>> >>>>On April 02, 2004 at 16:22:19, Jonas Bylund wrote: >>>> >>>>>Thank you very much for your detailed answers! >>>>> >>>>>When you say Diep already runs in windows mode, does that mean that it runs DOS >>>>>or "real" windows mode? (sorry about not being clear on that in my original >>>>>post) >>>>> >>>>>10GB for all the 3+4+5+6 tb's would be a HUGE success as would 20GB of course! >>>> >>>>It is also "vaporware". 3-4-5-6 tables will _not_ fit into 10 gigabytes. >>> >>>Yes but it is possible that tables that are enough to play 3-4-5-6 perfectly may >>>fit 10 gigabytes. >>> >>>Suppose that you have tables that have only 1/32 of the information in the >>>original 6-piece tables(it has information about exact distance to mate only if >>>the index of the position is divisible by 32). >>> >>>You can still use them in 1/32 of the positions in case that the index of the >>>position is in the table. >>> >>>In case that the index of the position is not divisible by 32 you can search >>>forward and in order to check if the index of the position is divisble by 32 you >>>do not need to look at the table. >>> >>>Now the question is if programs who use the smaller tables can practically play >>>6-piece positions perfectly or cannot do it. >>> >>>Uri >> >>Note also that nalimov admitted that he had no time to work on more efficient >>table for 6 pieces and the question is also how much can you compress the tables >>thanks to symmetry. > >Ever thought about how many possibilities there is to just compress 1 file? > >Take for example a PPM algorithm that knows about how your scheme works. > >Compression is a science in itself, actually IMHO more complex than >computerchess because you do not have infinite system time to compress real huge >files (like the big 3.6GB egtb files from DIEP). > >Chess has a limited number of positions possible. Latest ICGA journal estimate >was 10^43. > >I do not say there is more than 10^43 possibilities to compress a 3.6GB file >optimal. > >>In any case win/draw information can also be productive and in second thought I >>think that programs may fail in playing perfectly with only 1/32 of the >>information. > >You could convert the nalimov's for example to a format having >mate in 30, 31 .... n > >and everything under mate 30, so mate in 0 .. 29, you put it as 'mate'. > >You will figure out that you can play near perfect with that real soon. > >Sometimes a mate in 33 will get 34. > >I tried several maximin positions with diep without EGTBs and diep still mated >there very near optimal. That to my own surprise. Now imagine if you have >bittables available, there is 0% chance (not a perfect 0 but rounded 0) that it >will *not* mate :) > >Of course you will figure out a theoretic situation which simply will not occur >in practice. Just try it and you'll see. > >The chance that you will manage to escape to a 50 move rule is like 0.00000001. >I just do not see it happen in reality. > >For a start you need to get into KNN versus KP or something. > >Something really spectacular and always with 2 knights involved :) > >Just calculate from the TBS files how many draws there are *because of the 50 >move rule*. > >Reality is simply that not doing probes last few plies in the search is giving a >factor zillion more chances for incorrect behaviour than this :) > >>I thought that only 1/2 of the information may be enough becase it is enough to >>know positions when it is white to move so by the same logic only 1/32 may be > >Note it is a mystery to me where you got factor 32. > >Nalimov stores the hard ones in 2 bytes a position, diep stores 5 positions a >byte. > >Factor 10 savings. > >All egtbs with 1 byte a position for nalimov, it is a factor 5. I guessed that it is possible that you have also better compression of tablebases (for example when the result is almost always win for the stronger side) so I guessed factor of 32. > >>enough if you search deeper but in another thought I think that it is not so >>simple because the position when white to move may get index divisible by 2 but >>when I go only to divisble by 4 I cannot take care that the position of mate in >>x when x is even will get index that is divisible by 4. > >You should not be busy too theoretic. > >What do you want to do. Win the game, or play perfect chess? > >I want to win. You said in another post that today tablebases are not very important for that purpose. > >You? > >You want to buy in a few years a 2 TB harddisk to store all 6 men and then you >go have a try whether that's better than my 7 men? No I thought about the possibility not to use all the information in the nalimov tablebases but only part of it. Uri
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