Strelka

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Strelka (Стрелка, Russian for "little arrow"), a chess program by Jury Osipov which appeared as closed source engine in May 2007. Its successor, Strelka 2.0 was released as open source program in January 2008. Strelka 2.x became runner up behind WildCat at the 1st Computer Chess Championship of CIS Countries in 2008.

From the very beginning Strelka was suspected not to be original but derivative work as elaborated below. What kind of syllogism from the claims and statements by Vasik Rajlich, Fabien Letouzey, Jury Osipov and others applies, remains to be seen. However, it is more likely the ethical issues of computer chess programming are affected rather than the legal ones.

=Clone Suspicions= Almost immediately after Strelka's initial release, there were suspicions due to various similarities found in solving certain test-positions, that Strelka might be a clone of Rybka 1.0 Beta. The attempt by Sergei Markoff after reviewing its sources to declare Strelka original, seemed rather pointless due to the closed sources of the now commercial Rybka, but it was also confirmed by Bryan Hofmann , who according to Markoff is a compiler expert who also did Rybka compiles and was aware of its sources. Additionally, an "expert's opinion" was called from Dann Corbit to declare Strelka "clean". Fabien Letouzey, who was consulted by Dann, put a short note that Strelka 1.x source was not a verbatim copy of his open source engine Fruit, but revealed more details on that issue years later in January 2011, when he was long out of computer chess business and coincidentally got aware of the Strelka affair.

In the meantime, in July 2007, Jury Osipov admitted Strelka was based on Fruit rewritten to bitboards, and was successively improved in evaluation and search with correlation analysis of Rybka's assessment of the positions. Osipov further mentioned he studied Rybka using a disassembler, to achieve an even greater similarity, and that he felt that Vasik Rajlich likely walked the same path as he did, essentially to rewrite Fruit to bitboards and include material imbalance tables by Larry Kaufman.

=Strelka 2.0= In January 2008, the new Strelka version 2.0 released was open source, and everybody could compare Strelka 2.0 with the Fruit sources for the similarities or not, and whether the claims of Jury Osipov were correct. Notably, a few days later, Vasik Rajlich declared Strelka 2.0 a Rybka 1.0 Beta clone, which on the other hand raised further suspicions on the origins of Rybka.

=Strelka 5= In October 2011, Strelka 5 was released as closed source engine, according to Jury Osipov incorporating ideas of Rybka 3, Ippolit, Houdini, Critter and Stockfish, as well as own innovations.

=See also=
 * Belka
 * Claims that Strelka is Rybka
 * Fruit
 * Rybka

=Forum Posts=

2007

 * Наш новый движок Strelka!!! by SDChess, kasparovchess, May 04, 2007
 * New engine from Russia by Vladimir Medvedev, CCC, May 05, 2007
 * Something 'Fishy' about Strelka by Dann Corbit, CCC, May 08, 2007
 * Sergei Markow about Strelka by Werner Schüle, CCC, May 09, 2007
 * To put everything into place with Strelka by Sergei Markoff, CCC, May 10, 2007
 * Re: To put everything into place with Strelka by Alexander Schmidt, CCC, May 11, 2007


 * Strelka again by Sergei Markoff, CCC, May 11, 2007
 * The Strelka affair to date by Fernando Villegas, CCC, May 12, 2007
 * My review of Strelka Code by Bryan Hofmann, CCC, May 12, 2007
 * Strelka = Rybka 1.0 by DarkAvenger, Rybka Forum, July 07, 2007
 * Strelka 1.8 UCI released by Denis P. Mendoza, CCC, July 07, 2007
 * What Strelka tells about Rybka's nodecount and depth by Ernest Bonnem, CCC, July 09, 2007
 * Longer comments by V. Rajlich by Marc Lacrosse, CCC, July 10, 2007
 * More proof of Strelka cloning by Martin Bryant, CCC, July 10, 2007
 * Sensational! Y.Ossipov talking about STRELKA by Evgenii Manev, CCC, July 11, 2007
 * Strelka and source code experts by Matthias Gemuh, CCC, July 11, 2007
 * new translation of J.Osipov statement in KasparovChess forum by Evgenii Manev, CCC, July 12, 2007
 * Fruit, Rybka, Strelka final conclusion! (I hope) by Michael Sherwin, CCC, July 13, 2007 » Rybka, Strelka
 * About strelka1.8 sources by Uri Blass, CCC, October 01, 2007
 * Strelka 1.8 source code review by Bryan Hofmann, CCC, October 01, 2007
 * Strelka - clone status by Dann Corbit, CCC, October 03, 2007
 * About the code of strelka by Uri Blass, CCC, October 10, 2007
 * Strelka - Open source by Evgenii Manev, CCC, December 29, 2007

2008

 * Strelka 2.0 by Vasik Rajlich, Rybka Forum, January 11, 2008
 * Re: Strelka 2.0 pg 4 by Anthony Cozzie, Rybka Forum, January 11, 2008
 * What's Strelka's Secret Sauce? by Steve Maughan, CCC, January 11, 2008
 * A comment of Yuri Osipov about V.Rajlich statement by Evgenii Manev, CCC, January 12, 2008
 * ethical dilemma by Gerd Isenberg, CCC, January 12, 2008
 * Rajlich/Osipov/Rybka/Strelka/Answers by Convekta by Eduard Nemeth, CCC, January 17, 2008 » Rybka, Convekta
 * Toga/Glaurung/Strelka Prunings/Reductions by Edsel Apostol, CCC, January 31, 2008 » Toga, Glaurung, Pruning, Reductions
 * Anthony Cozzie speak ! by Silvian, Rybka Forum, February 03, 2008
 * Strelka cannot see mate in 1 by Uri Blass, CCC, March 06, 2008
 * Strelka Reverse Engineered from Rybka: Details Examined by Rick Fadden, CCC, May 01, 2008
 * Fruit 2.1 vs Strelka 2.0 by Norman Schmidt, CCC, August 18, 2008 » Fruit
 * Rybka 1.0 vs. Strelka by Zach Wegner, CCC, August 19, 2008
 * counting similiarities between strelka2.0 and fruit2.1 by Uri Blass, CCC, August 22, 2008
 * Strelka = Rybka 1.0 =Fruit 2.1 = Toga?? Oh how disappointing by Oliver Brausch, CCC, October 21, 2008

2011

 * Fabien's open letter to the community by Tord Romstad, CCC, January 23, 2011
 * Fabien's open letter to the community by Tord Romstad, Open Chess Forum, January 23, 2011
 * Revisiting Strelka/Rybka by Mark Watkins, Open Chess Forum, January 25, 2011
 * Re: Strelka 2.0 B running for the IPON ... by Jury Osipov, CCC: Tournaments and Matches, January 27, 2011
 * Attack of the clones | ChessVibes by David Levy, 19 February, 2011
 * Strelka 5 by Yuriy Osipov by Slavik Pavloff, CCC, October 15, 2011 » Houdini
 * Re: Komodo 4 on long time control by Richard Vida, CCC, December 04, 2011 » Houdini, Komodo

2012 ...

 * strelka 5.6 by Don Dailey, CCC, February 06, 2013 (registration required)
 * New Strelka 5.7 MP Available... by Steve Maughan, CCC, October 02, 2013
 * Strelka new edition by Norbert Raimund Leisner, CCC, May 01, 2014

=External Links=

Chess Engine

 * Strelka (chess engine) from Wikipedia
 * Strelka controversy from Wikipedia
 * Главная страница
 * Strelka5


 * Strelka Юрия Осипова, Россия from sdchess.ru
 * Download by sdchess.ru
 * Strelka in CCRL 40/40

Misc

 * Strelka disambiguation page from Wikipedia
 * Korabl-Sputnik 2 with Belka and Strelka from Wikipedia

=References= Up one Level