Nalimov Tablebases

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Nalimov Tablebases, are 3-to-6-man endgame tablebases developed by Eugene Nalimov, providing depth to mate information. First published for up to 5-man in late 1998, 6-man files were released subsequently over the years and 6-man chess was finally solved in 2005. Nalimov Tablebases apply a more efficient indexing scheme than previous tablebases, and were further compressed into 8 KiB blocks exploiting common subsequences and Huffman coding as contributed by Andrew Kadatch, doing less file I/O which gets replaced by fast on-the-fly decompression. This allows fast probing not only at the root, but during the search inside the tree, further utilized by an own LRU cache despite keeping TB files in the page cache by the operating system. For endgames with pawns of both sides, the TBs consider en passant with disjoint index ranges.

=File Sizes= 5-man Nalimov Tablebases are about two times smaller than Edwards' Tablebases when uncompressed, and about eight times smaller than Edwards' when compressed.

=Savings= In CCC, Eugene Nalimov gave a brief summary, how to realize the space savings :

=License= In the late 90s Nalimov Tablebases became defacto standard and were used in many commercial, private and free chess engines and GUI's. A reference implementation by Eugene Nalimov and Robert Hyatt was realized in Crafty, with Tablebases and probing code available from Bob Hyatt's site. Probing could easily incorporated into own chess engines, however the license policy requires explicit permission by Eugene Nalimov.

=See also=
 * Bitbases
 * Edwards' Tablebases
 * Gaviota Tablebases
 * Lomonosov Tablebases
 * Scorpio Bitbases
 * Syzygy Bases
 * Thompson's Databases

=Publications=
 * Eugene Nalimov, Guy Haworth, Ernst A. Heinz (2000). Space-Efficient Indexing of Chess Endgame Tables. ICGA Journal, Vol. 23, No. 3, postscript
 * Eugene Nalimov, Guy Haworth, Ernst A. Heinz (2001). Space-efficient Indexing of Endgame Tables for Chess. Advances in Computer Games 9
 * Guy Haworth, Peter Karrer, John Tamplin, Christoph Wirth (2001). 3-5-man chess: Maximals and mzugs. ICGA Journal, Vol. 24, No. 4
 * Eugène Nalimov (2002). Chess Endgame Tablebases. Invited Lecture, 7th Computer Olympiad Workshop
 * Guy Haworth (2005). 6-Man Chess Solved. ICGA Journal, Vol. 28, No. 3

=Forum Posts=

1998 ...

 * Tablebases by Eugene Nalimov, CCC, August 28, 1998
 * Program for new TB by Dr. Eugene Nalimov ? by Michael Diosi, rgcc, November 6, 1998
 * Nalimov's TBs: one question by Jouni Uski, CCC, November 18, 1998
 * Re: Nalimov's TBs: one question by Eugene Nalimov, CCC, November 18, 1998


 * Q: Nalimov EGTB? by Dennis Breuker, CCC, August 05, 1999
 * Re: Q: Nalimov EGTB? by Eugene Nalimov, CCC, August 05, 1999


 * Nalimov TB caching ? by Ulrich Türke from CCC, August 06, 1999
 * EGTBs by Frank Phillips, CCC, September 03, 1999
 * difference betrween nalimov and thompson EGTB by Rajen Gupta, CCC, December 10, 1999
 * Re: difference betrween nalimov and thompson EGTB by Frederic Friedel, CCC, December 11, 1999

2000 ...

 * Nalimov-EGTBs in ANSI-C? by Heiner Marxen, CCC, January 21, 2000
 * Usage of egtb.cpp in GPL software (Amy, ExChess, ...) by Gian-Carlo Pascutto, CCC, December 05, 2000 » Amy, EXchess
 * Re: Usage of egtb.cpp in GPL software (Amy, ExChess, ...) by Eugene Nalimov, CCC, December 05, 2000


 * Nalimov endgames by Jean-Christophe Weill, CCC, February 20, 2001
 * Nalimov's EGTBs (long post with code) by Heiner Marxen, CCC, October 13, 2001
 * Nalimov TB question by Bas Hamstra, CCC, November 11, 2001
 * Questions about the new Nalimov tablebase files... by Dann Corbit, CCC, December 12, 2002
 * Compressed Nalimov EGTBs by Leonardo Ljubicic, rgcc, November 18, 2003
 * Bug/glitch in Nalimov Code (and in Wilhelm)? by Dieter Bürßner, CCC, May 09, 2004
 * To Eugene Nalimov: Copyright of Tablebase files by Karl-Heinz Milaster, CCC, June 05, 2004
 * Are nalimov EGTB's a copyright from chessbase? by Vincent Diepeveen, CCC, June 07, 2004
 * Enpassant in Nalimov by Henry Hongdoyo, CCC, October 25, 2004

2005 ...

 * Subject: Problem (small bug?) with Nalimov TBs by Dieter Bürßner, CCC, January 23, 2005
 * To sumarize this by Thomas Mayer, CCC, August 17, 2005
 * For Eugene Nalimov: EGTB Request by Vasik Rajlich, CCC, December 16, 2005
 * smp and nalimov egtb, how to make it work? by Volker Böhm, CCC, February 23, 2006
 * Chessbase releases 9 dvds on Nalimov 6-piece database 43 gb by Daneil Johnson, CCC, February 23, 2006
 * Nalimov access with Vasik Rajlich, Rybka Forum, January 9, 2007
 * Nalimov Tablebases by Terry Giles, CCC, July 02, 2007
 * Nalimov EGTB by cyberfish, CCC, October 19, 2008
 * 6-men (64 bit) Nalimov EGTB generator by Gian-Carlo Pascutto, CCC, September 13, 2009
 * Nalimov EGTB probes skeleton code by Joshua Shriver, CCC, December 17, 2009

2010 ...

 * Nalimov and memory for indexes (are you aware?) by Miguel A. Ballicora, CCC, March 01, 2010
 * Question for Nalimov experts by Mincho Georgiev, CCC, April 10, 2010
 * Gaviota EGTB in Houdini 1.5 + contacting Eugene Nalimov by Robert Houdart, CCC, December 01, 2010
 * Nalimov 6 men ... by Michael Diosi, CCC, January 12, 2013
 * Nalimov by Sune Larsson, CCC, May 22, 2013

2015 ...

 * Nalimov EGTB problem related to DTM? by Kai Laskos, CCC, February 14, 2016 » DTM
 * Re: Nalimov EGTB problem related to DTM? by Ronald de Man, CCC, February 14, 2016


 * Nalimov egtb probing code by Fabio Gobbato, CCC, May 16, 2016

=External Links=

General

 * Tablebases by Eugene Nalimov
 * Nalimov Tablebases from Arena Chess GUI
 * Eugene Nalimov: Winner of the ChessBase Award and Guest of Honor in Maastricht by Eric van Reem, ChessBase events, July 9, 2002 (archived)
 * Theoretical statistics for chess endgames with up to five pieces by Ulrich Thiel
 * Engines and endgame tablebases by Albert Silver, ChessBase News, December 12, 2013

Online Lookup

 * Endgame Nalimov Tablebases Online - ChessOK
 * Nalimov EGTB from GMchess.com
 * Nalimov Tablebase server (DTM) by Lokasoft
 * Web Query for Nalimov Endgame Tablebases from Knowledge4IT by Eiko Bleicher

Download

 * Index of /hyatt/crafty/TB hosted by Robert Hyatt
 * Endgame Tablebases Online - 6-men endgame analysis free for everyone by Kirill Kryukov (3,4,5,6 pieces - via emule)
 * tablebase.sesse.net by Sesse

=References=

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