Author: Vincent Diepeveen
Date: 10:16:24 04/02/04
Go up one level in this thread
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.
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