Author: Eric Oldre
Date: 15:07:47 01/06/05
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On January 06, 2005 at 14:33:33, Norm Pollock wrote: >On January 06, 2005 at 13:20:27, Eric Oldre wrote: > >>I have added the ability to add opening books to my latest version of Latista. >>I'll release it once I create a decent opening and add a couple other smaller >>features. >> >>So far I created a book my parsing the gm2600.pgn file and saving all positions >>which occur at least 5 times. >> >>This is certainly much better than no book at all but leaves much much room for >>improvment I'm sure. >> >>What general advice do you book makers have for me? >> >>Thanks, >>Eric > >First, may I suggest that you have two opening books, one for white's moves and >one for black's moves. This way you can "feed" pgns into white's book that have >white winning (and drawing). Likewise for black's book, you can "feed" pgns into >black's book that have black winning (and drawing). currently i store the number of white wins, black wins, and draws for each position in the book. I can see how it would probably be better from a space/memory perspective to create 2 separate. > >Second, I would also use more recent pgns than in gm2600.pgn because current >over-the-board players know what the latest changes are in openings, and they >have the benefit of computer analysis. (Btw, I have made a pgn collection of >recent games that is available at crafty-chess.com in the user download >section.) Also limiting the book to games with both players elo 2600+ will mean >a small book, unless you allow the number of position occurrences to be very >small (see next paragraph). Thanks Norm, I'll download that tonight! > >Third, no matter how hard you try, bad opening moves are going to be in the >opening book. The question is how to limit the number of them. I believe the >best and only reliable approach is to have a very high number for the number of >occurrences before including that position in the book. I recommend that you use >12 occurrences if you are starting from a pgn collection of 60K games. > >Another approach to quality control is "book learning". I'm not a fan of book >learning. All I think it does is adjust the statistics for each position (# >occurrences, win-lose-draw) based on the engine's performance. But if your >engine is playing an engine 100 elo stronger, why punish the opening because >your engine lost. The opening might have been excellent. Likewise, why reward a >poor opening because your engine defeated a weaker opponent. I had thought about trying to do book learning at some point but had thought of this also, I'll put it on the "maybe someday" list. > >Another point. Some pgn collections have loads of old games, low elo games, >duplicate games, twin games, blitz, rapid, lightning, email, Internet, >simultaneous exhibition games and grandmaster short draws. My collection that I >mentioned before is one of those that has filtered those types of games out. So >be careful. > >Good luck, > >Norm
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