Author: Arild Fredriksen
Date: 14:50:12 02/04/02
ChessliB proudley presents Mr. E. Lunsens Opening Book The authors words: Definition ========== Ever since I got access to internet in 1995 I have been downloading and collecting chess game histories. My chess database contains exactly 621,368 games in which both players have an Elo rating over 2000 and was especially prepared to build the general reference opening book of any chess program. All opening lines were truncated after the 80 th ply which is more than sufficient to cover any possible opening under the current chess rules. Exact doubles were deleted according to the algorithms implemented in Chessbase with the following parameters: Players: ignore Tournaments: ignore Moves: exact In the case of exact doubles the average Elo ratings of white and black players respectively were used in order to avoid underrating / overrating. Other search algorithms may find fuzzy doubles with game histories that are not completely identical but for the sake of completeness fuzzy doubles were included in the database. Headers ======= All games contain the following headers: Result Eco code White Elo Black Elo Other headers were stripped since they are only for human use and of no use to chess programs.These other headers only form clutter in opening books that makes it harder and slower for the chess program to browse the opening tree as is the case in Power Book and other native opening books by Chessbase. Consequently it is possible to search the database by position, by Elo rating, by number of moves, by Eco code and by result. Similarity ========== Similar games are games with identical game histories up to and including the 80 th ply but differ in later plies. In the database similar games are logically treated as exact doubles. However, the average Elo ratings of white and black players respectively were used in order to avoid underrating / overrating. Development =========== The project was started from scratch in November 1995 and completed in January 2002. As of the month of March 1997 I was assisted by several online friends who searched and selected rare, unconventional and unpublished games from various resources, databases, chess studies and rare chess books. The database does not contain the games of the computer chess tournaments that I used to organize a couple of years ago since those were blitz tournaments and such games would reduce the relative playing strength. Selection ========= Games were selected to be included in the opening book according to the principle of initial brute force gradually tapering to deep forward pruning with ample ramifications in each ply. Deep proliferation of each ramification was introduced from the very outset what guarantees crossovers and interlinking of all lines and openings. The opening book contains exactly 7,572,429 unique positions in exactly 431,916 included games. Some games of the database were not included in the opening book since they would reduce the relative playing strength. The opening book contains only games in which both players have an Elo rating over 2200 whereas Power Book by Chessbase contains also games in which one player has an Elo rating over 2000 and the other player has an Elo rating below 2000. Short and incomplete games were also exluded as well as games containing tactical opening blunders. The opening book represents the closest possible approach to ideal proportion between quality of playing strength and comprehensiveness of quantity of included games. Software ======== The following sofware was used during the development of the database and opening book: ChessBase Chess Assistant CDB Scid Sankit Extract Pgn Edit Mbase Normal Ecoclass Chessbase Powertools Ultra Edit Vedit Plus WinAce Power Archiver Interface ========= The opening book was developed and tested in the Chessbase interface that is available from: http://www.chessbase.com The opening book was tested with several chess engines and against several native opening books. The database is to be used to build the opening book of chess programs that are not compatible with the Chessbase interface. Distribution ============ The provided material was compressed with WinAce in ace format that provides the maximum possible compression ratio. WinAce is available for download from: http://winace.com WinAce is easier to work with than WinZip and provides the possibility to create and extract both ace and zip files. Disclaimer ========== The database and opening book were built from scratch and no copyrighted material was involved. Chess is only my hobby and consequently the provided material is freeware and comes as is without any warranty by it's author and is to be distributed for free without any modifications. If you have any questions or suggestions, please keep in mind that on the average I reply to 10 to 15 Email messages a day and consequently my Email address is not provided here in order to avoid spam mail. Questions on the provided material or on computer chess in general can be posted at the Computer Chess Club that I occasionally visit. The Computer Chess Club is located at: http://www.icdchess.com/ Even if you do not immediately receive a reply, be sure that your message will be taken into account and acted upon as soon as the occasion arises to provide new updates to the provided material. Hopefully the provided material will further the mathematical and scientific approach to computer chess. Acknowledgements ================ Credits are provided in this section in chronological order of first online contact. I would like to express my appreciation to all online friends who sent in games but especially to Vladimir Sokolov of the University of Rostov who was involved with the project since 1997 and who managed to select and send in more than 120,000 games without a single double. Also, I'm grateful to Dr. Hyatt of the University of Alabama, Rob Weir, Paul Onstad and Dann Corbit for their online help and advice and to Arild Fredriksen of the University of Bergen for hosting the provided material on the FTP server of the University of Bergen. Last but not least, a special mention for Dell D8100, Intel 1500 Mhz and all their silicon colleagues who behaved impeccably throughout. E. Lunsen February 2002 http://www.uib.no/people/pfvaf/chesslib/
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