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'''Syzygy Bases''', <ref>[http://www.talkchess.com/forum/viewtopic.php?t=47681&start=45 Re: New 6-piece tablebases] by [[Ronald de Man]], [[CCC]], April 10, 2013</ref><br/>
a compact six piece endgame database developed by [[Ronald de Man]], published on April 01, 2013. Since August 2018, '''seven piece''' Syzygy Bases are available after an effort by [[Bojun Guo]] started in March 2018 <ref>[http://talkchess.com/forum3/viewtopic.php?f=7&t=66797&start=472 Re: 7-men Syzygy attempt] by [[Bojun Guo]], [[CCC]], August 19, 2018 </ref>. The generator is released under the [[Free Software Foundation#GPL|GNU General Public License Version 2]], the [[Thread|thread safe]] probing code is released without restrictions <ref>[http://www.talkchess.com/forum/viewtopic.php?t=47681 New 6-piece tablebases] by [[Ronald de Man]], [[CCC]], April 01, 2013</ref> .
=Data=
==7-man==
Ronald de Man wasn't initially interested in the creation of 7-men Syzygy Based <ref>[http://kirill-kryukov.com/chess/discussion-board/viewtopic.php?f=6&t=7618#p83771 Re: 7-piece syzygy] by [[Ronald de Man|syzygy]], [[Computer Chess Forums|CCRL Discussion Board]], July 03, 2014</ref> since the generation would require about 1 TB of RAM, too expensive at that time. Generation time would be about 64 x per table, which means around 175 x time total <ref>[http://kirill-kryukov.com/chess/discussion-board/viewtopic.php?f=6&t=7396#p83338 Re: Syzygy tb generator for windows] by [[Ronald de Man|syzygy]], [[Computer Chess Forums|CCRL Discussion Board]], June 01, 2014</ref>.His original generator could not create them. But in 2018, he supported [[Bojun Guo]] in his 5-month attempt to generated them <ref>[http://www.talkchess.com/forum/viewtopic.php?t=66797 7-men Syzygy attempt] by [[Bojun Guo]], [[CCC]], March 10, 2018</ref>. His hardware was estimated at over US$ 90K. In August of 2018 their creation was completed<ref>[https://syzygy-tables.info/ Powered by Ronald de Man's Syzygy endgame tablebases, 7-piece tables generated by Bojun Guo and a public API hosted by lichess.org], August 19, 2018</ref><ref>[http://tablebase.lichess.ovh/tables/standard/7/ Index of /tables/standard/7/ on lichess], August 19, 2018</ref>.
==Checksums==
Syzygy endgame files may contain 128-bit checksum keys at the end of those files. It also has its own code for checksums (based on Google's cityhash library).
=Search=
==At the Root==
At the [[Root|root]], since pure DTZ50-optimal play (i.e. minimaxing the number of moves to the next [[Captures|capture]] or [[Pawn Push|pawn move]] by either side) can be very unnatural, it might be desirable to let the engine search on the winning moves until it becomes clear that insufficient progress is being made and only then switch to DTZ-optimal play (e.g. by detecting [[Repetitions|repetitions]] and monitoring the [[Halfmove Clock|halfmove clock]]) <ref>[http://www.talkchess.com/forum/viewtopic.php?t=47681&start=8 Re: New 6-piece tablebases] by [[Ronald de Man]], [[CCC]], April 05, 2013</ref>.
=Pros & Cons=
* Hard to understand and contribute to the project. ETGB itself is a hard topic. Syzygy EGTB has also integrated with many advanced techniques/tricks. It is written in old-style C language. All make it become very hard to understand and/or modify to improve or for other purposes
* [[Endgame Tablebases#DTZ50|DTZ50]] metric may lead the engines to win in much longer and ugly ways, compared with [[Endgame Tablebases#DTM|DTM]] one
=Data publish=
[[Jon Dart]] has a fork of Fathom with some bug fixes and enhancements <ref>[https://github.com/jdart1/Fathom jdart1/Fathom · GitHub] by [[Jon Dart]]</ref>, also supporting 7-man <ref>[http://www.talkchess.com/forum3/viewtopic.php?f=7&t=70568 7-man Syzygy support in Fathom] by [[Jon Dart]], [[CCC]], April 23, 2019</ref>.
==Pyrrhic=='''Pyrrhic''' is a cleaned up Fathom by [[Andrew Grant]], introduced in August 2020 <ref>[http://www.talkchess.com/forum3/viewtopic.php?f=7&t=74809 Pyrrhic, Fathom for Humanoids] by [[Andrew Grant]], [[CCC]], August 16, 2020</ref> <ref>[https://github.com/AndyGrant/Pyrrhic/ GitHub - AndyGrant/Pyrrhic: Fathom, for Humanoids]</ref>.
=Elo gain=
[[Stockfish#Fishtest|Fishtest]] team revealed a test with [[Stockfish]] (SF10dev) at 10+0.1, with all Syzygy WDL files on RAM, testing using none(0), 4, 5, and 6 man TB in a round-robin tournament (SF10dev)<ref>https://github.com/glinscott/fishtest/wiki/UsefulData Collection of useful data concerning SF</ref>.
{| class="wikitable"
If the engine needs to know the DTZ value (which is only necessary when a TB root position has been reached), the probing code may have to do a 1-ply search to get to the "right" side of the DTZ table.
For 6-piece TBs, DTZ is 81.9GB when storing only the smaller side of each table. Storing both sides might require perhaps 240GB.
=Endgame News=
and further gives some news about early software bugs and glitches concerning [[ChessBase]] products, and the importance of [https://en.wikipedia.org/wiki/MD5 MD5] to check the EGT integrity.
=See also=
: [http://talkchess.com/forum3/viewtopic.php?f=7&t=66797&start=472 Re: 7-men Syzygy attempt] by [[Bojun Guo]], [[CCC]], August 19, 2018
* [http://www.talkchess.com/forum/viewtopic.php?t=66830 Syzygy implementations of top engines] by [[Kai Laskos]], [[CCC]], March 14, 2018
* [http://www.talkchess.com/forum/viewtopic.php?t=67122 Probing the Syzygy tablebase - beginners question] by [[Andreas Matthies]], [[CCC]], April 16, 2018
* [http://www.talkchess.com/forum3/viewtopic.php?f=7&t=67536 DTM50] by [[Ronald de Man]], [[CCC]], May 22, 2018
* [http://www.talkchess.com/forum3/viewtopic.php?f=7&t=68236 Re-Pair compression questions] by [[Rein Halbersma]], [[CCC]], August 17, 2018
* [http://www.talkchess.com/forum3/viewtopic.php?f=7&t=71625 Syzygy 7 man advice please] by Barry Clements, [[CCC]], August 21, 2019
* [http://www.talkchess.com/forum3/viewtopic.php?f=7&t=71896 Syzygy DTZ data explaination?] by [[Pham Hong Nguyen|Nguyen Pham]], [[CCC]], September 23, 2019
==2020 ...==
* [http://www.talkchess.com/forum3/viewtopic.php?f=7&t=73598 Almost perfect DTM tablebase] by [[Dann Corbit]], [[CCC]], April 08, 2020
* [http://www.talkchess.com/forum3/viewtopic.php?f=7&t=74809 Pyrrhic, Fathom for Humanoids] by [[Andrew Grant]], [[CCC]], August 16, 2020
* [http://www.talkchess.com/forum3/viewtopic.php?f=7&t=75396 EGTB compression] by [[Dann Corbit]], [[CCC]], October 14, 2020 <ref>[https://en.wikipedia.org/wiki/LZ4_(compression_algorithm) LZ4 (compression algorithm) from Wikipedia]</ref> <ref>[https://en.wikipedia.org/wiki/Zstandard Zstandard from Wikipedia]</ref>
* [http://www.talkchess.com/forum3/viewtopic.php?f=2&t=75487 Syzygy bases ... question to "Syzygy Probe Depth"] by [[Frank Quisinsky]], [[CCC]], October 21, 2020
=External Links=
* [https://github.com/jdart1/Fathom jdart1/Fathom · GitHub] by [[Jon Dart]] (with some bug fixes and enhancements)
* [https://github.com/ljgw/syzygy-bridge GitHub - ljgw/syzygy-bridge: Java bridge to use the Syzygy Tablebases via JNI] by [[Laurens Winkelhagen]] » [[FrankWalter]]
==Pyrrhic==
* [https://github.com/AndyGrant/Pyrrhic/ GitHub - AndyGrant/Pyrrhic: Fathom, for Humanoids] by [[Andrew Grant]]
==Online Lookup==
* [https://www.chessdb.cn/queryc_en/ Chess Cloud Database Query Interface] by [[Bojun Guo|noobpwnftw]] <ref>[http://www.talkchess.com/forum3/viewtopic.php?f=2&t=71764 ChessDBCN] by [[Bojun Guo|noobpwnftw]], [[CCC]], September 09, 2019</ref>
* [https://syzygy-tables.info/ Syzygy endgame tablebases Web Interface]
==ChessBase==
