Author: Peter Fendrich
Date: 09:09:06 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? > >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. A very good idea that I support to 100%! It should even be possible to write an adapter or open source code that translates from the epd to the egtb format. /Peter
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