Author: Mridul Muralidharan
Date: 12:13:42 04/02/04
Go up one level in this thread
On April 02, 2004 at 13:16:24, Vincent Diepeveen wrote: >On April 01, 2004 at 21:15:43, Dann Corbit wrote: > >>On April 01, 2004 at 20:40:58, Eugene Nalimov wrote: >> >>>On April 01, 2004 at 19:05:09, Dann Corbit wrote: >>> >>>>On April 01, 2004 at 18:38:59, Sune Fischer wrote: >>>> >>>>>On April 01, 2004 at 18:29:27, Dann Corbit 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. >>>>>> >>>>>>I have an idea that I think would be helpful if you should be so kind as to >>>>>>perform it. >>>>>> >>>>>>Write a scanner that reads your wonderful EGTB files and spits out a two bit >>>>>>state only for each position (won/lost/drawn/broke) to create bitbase files. >>>>>> >>>>>>The reason I suggest it is that a bazillion programmers won't have to reinvent >>>>>>the wheel. >>>>>> >>>>>>I suggest the use of the bitbase files early in the search (completely pulled >>>>>>into ram) and then EGTB at the leaves if the bitbase indicates it is worthwhile. >>>>> >>>>>You must mean it the opposite way, bitbases at the leaves and EGTBs a near root? >>>>> >>>>>I think it would be better to use bitbases in the entire search and only use >>>>>full EGTBs when the position is at the root. >>>>> >>>>>Or, if you want the search to eventually return mate scores, probe EGTBs when >>>>>bitbases say it is won and beta>=mate_bound or bitbases says it lost and >>>>>alpha<=-mate_bound. >>>>>Perhaps probing directly into EGTBs when window allows it would be faster, >>>>>matter of tuning of course. >>>> >>>>I guess I had not thought about it carefully enough. I imagined using bitbases >>>>to get a won/lost/drawn opinion (at all nodes). But unless you know the exact >>>>value of the leaves, I don't see how you can choose the best move. >>>> >>>>I imagined something like this: >>>>If the best evaluation is drawn or lost, who cares. Do whatever move is among >>>>the suggested list. >>>>If the best evaluation is won, then: >>>>Examine the bottom leaves that are won and perk the correct values back up. >>>> >>>>How will we otherwise find the true value? I am afraid I don't understand how >>>>it can work. >>> >>>In my "TODO" list. But let me finish 6-men TBs first... >>> >>>Simple way is to keep both w/d/l and full tables. You need to probe full table >>>only when position is OTB. Otherwise you probe w/d/l table. W/d/l tables are >>>smaller, and relevan ones can be always loaded to RAM, so you can probe them >>>everywhere in the search, including Q-search. >>> >>>Probing of the full TBs can be much slower than it is now, probably ~1 sec >>>should be fine. In theory that allows to use better decompression algorithm. >>> >>>And you don't need 2 bits per position. 1.6 bits are enough (5 positions per >>>byte). >> >>How about an interface to your EGTB system that takes a standard EPD string as >>input? > >The problem is that everyone must first post onto CCC to get permission to use >his code. Email he never answers until there is a posting onto CCC. Only from 1 >american author i know he got directly permission at his first email. The others >after half a year or so post onto CCC and only then get an answer. > >So your only problem is not the EPD, but the legal permission for each user to >use that program, even if it is put at a commercial cdrom. > >As shipping an email will not get answerred. I have not heard a single european >programmer so far who got permission by email within 6 months. > >>That way, it would be really simple for people to interface to it that have not >>already done so. Just about every chess program has a "convert board position >>to EPD" function of some kind. I got a very quick reply from both Dr. Hyatt (1 day) and Eugene (< 1 week). Even Andrew Kadatch was very quick to grant me permission (Eugene forwarded to him - i think he responded within same day after Eugene forwarded the mail). So maybe you know of atleast one person who did not wait for 6 months and who did not have to retry multiple times :) Mridul
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