Author: Ricardo Gibert
Date: 18:17:55 01/30/02
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On January 30, 2002 at 19:28:46, Dann Corbit wrote: >On January 30, 2002 at 19:11:28, Ricardo Gibert wrote: >[snip] >>>Or (tangentially) alpha-beta files can be created from analyzed chess positions. >>> So that you would know "this position is not worse than..." by doing a lookup. >>>This idea sounds pretty silly (the alpha-beta files) but it might be worth a >>>look in the opening phase or the mid-endgame. >> >>Some of your commentary looks like it was inserted into the wrong post by >>mistake to me. I can't tell if you are agreeing or disagreeing with much of what >>I wrote. >> >>In any case, I would just like to add that the idea of maintaining a database of >>middlegame positions is not reasonable, since the astronomically low hit rate >>does not justify the even tiny amount of time expended trying to look them up. > >Exactly. I agree one hundred percent. Which is why i said "opening" or >"mid-endgame" instead. By mid-endgame, I mean a board with perhaps 8-10 >chessmen on it. I mistook your "mid-endgame" for "middlegame". My bad. But let's assume all you want to set up is a database of "only" 8-man positions. It takes 4 + 7*6 = 46 bits to represent each one. Rounding down that's about 6E13 positions. Now lets say you set up your database with 10 trillion positions. We'll overlook the problem of populating it with information ;-) Thanks to a "brilliant" scheme that lets 1 position represent an equivalence class of say 100 positions on average, you only need to store 100 billion positions on disk at only one byte per position. That's an impressive 1E11 positions. But this means you will only have 1E11/6E13 = 1 in 600 chance of scoring a hit. How practical is that? It isn't. With Nalimov EGTBs, you *know* you will get a hit with 5 or fewer pieces to look up. With 8-man you won't. But let's say you get your hit, then what will you do on the positions following the current one. Do you expect to find those too in this database? Aside from my 2nd, 3rd & 4th paragraphs making some rather unreasonable assumptions to make things "close" for this new idea, what happens when we consider 9-man and 10-man databases? Kinda gets tougher doesn't it? > >>Too many possible chess positions and too little memory relatively speaking. Not >>even having 1 position represent an equivalence class of a hundred or so >>positions changes this. > >No arguments there.
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