Strelka

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|| [[image:Strelka_at_essendon.jpg width="340" height="222" link="http://commons.wikimedia.org/wiki/File:Strelka_at_essendon.jpg"]] ||~   || **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 Engines|open source program]] in January 2008. Strelka 2.x became runner up behind [[WildCat]] at the [[CCCCISC 2008|1st Computer Chess Championship of CIS Countries]] in 2008. 

From the very beginning Strelka was suspected not to be original but [[http://en.wikipedia.org/wiki/Derivative_work|derivative work]] as elaborated below. What kind of [[http://en.wikipedia.org/wiki/Syllogism|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 [[http://en.wikipedia.org/wiki/Ethics|ethical]] issues of computer chess programming are affected rather than the [[http://en.wikipedia.org/wiki/Legal|legal]] ones. ||
|| Strelka [[https://en.wikipedia.org/wiki/Sputnik_5|on tour]] <ref>[[https://en.wikipedia.org/wiki/Russian_space_dogs#Belka_and_Strelka|Soviet space dogs from Wikipedia - Belka and Strelka]]</ref> ||~   ||^   ||
[[toc]]
=Clone Suspicions= 
Almost immediately after Strelka's initial release, there were suspicions due to various similarities found in solving certain [[Test-Positions|test-positions]] <ref>[[http://www.talkchess.com/forum/viewtopic.php?p=116315|Re: My Tests with Strelka]] by [[Eduard Nemeth]], [[CCC]], May 07, 2007</ref> <ref>[[http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=116341|Re: TO BE OR NOT TO BE]] by [[Michael Scheidl|Mike Scheidl]], [[CCC]], May 07, 2007</ref>, that Strelka might be a clone of [[Rybka|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]] <ref>[[http://www.talkchess.com/forum/viewtopic.php?t=13661|Sergei Markow about Strelka]] by Werner Schüle, [[CCC]], May 09, 2007</ref>, but it was also confirmed by [[Bryan Hofmann]] <ref>[[http://www.talkchess.com/forum/viewtopic.php?t=13716|My review of Strelka Code]] by [[Bryan Hofmann]], [[CCC]], May 12, 2007</ref><ref>[[http://www.talkchess.com/forum/viewtopic.php?t=16836|Strelka 1.8 source code review]] by [[Bryan Hofmann]], [[CCC]], October 01, 2007</ref>, who according to Markoff is a compiler expert who also did Rybka compiles and was aware of its sources <ref>[[http://www.talkchess.com/forum/viewtopic.php?t=13676|To put everything into place with Strelka]] by [[Sergei Markoff]], [[CCC]], May 10, 2007</ref> . Additionally, an "expert's opinion" was called from [[Dann Corbit]] to declare Strelka "clean" <ref>[[http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=117531&t=13716|Re: My review of Strelka Code]] by [[Dann Corbit]], [[CCC]], May 12, 2007</ref><ref>[[http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=129446&t=14953|Re: Is strelka a clone?]] by [[Dann Corbit]], [[CCC]], July 09, 2007</ref>. [[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 <ref>[[http://www.talkchess.com/forum/viewtopic.php?t=37762|Fabien's open letter to the community]] by [[Tord Romstad]], [[CCC]], January 23, 2011</ref> <ref>[[http://www.open-chess.org/viewtopic.php?f=3&t=1014|Fabien's open letter to the community]] by [[Tord Romstad]], [[Computer Chess Forums|Open Chess Forum]], January 23, 2011</ref> .

In the meantime, in July 2007, Jury Osipov admitted Strelka was based on [[Fruit]] rewritten to [[Bitboards|bitboards]], and was successively improved in [[Evaluation|evaluation]] and [[Search|search]] with correlation analysis of Rybka's assessment of the positions. Osipov further mentioned he studied Rybka using a [[http://en.wikipedia.org/wiki/Disassembler|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 Tables|material imbalance tables]] by [[Larry Kaufman]] <ref>[[http://www.talkchess.com/forum/viewtopic.php?t=15013|new translation of J.Osipov statement in KasparovChess forum]] by Evgenii Manev, [[CCC]], July 12, 2007</ref>.

=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 <ref>[[http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=3006|Strelka 2.0]] by [[Vasik Rajlich]], [[Computer Chess Forums|Rybka Forum]], January 11, 2008</ref> , 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|Rybka 3]], [[Ippolit]], [[Houdini]], [[Critter]] and [[Stockfish]], as well as own innovations <ref>[[http://strelkachess.narod.ru/Strelka5.html|Народ.Ру: Осипов Юрий]] (Russian)</ref> <ref>[[http://www.talkchess.com/forum/viewtopic.php?t=40777|Strelka 5 by Yuriy Osipov]] by Slavik Pavloff, [[CCC]], October 15, 2011</ref>.

=See also=
* [[Belka]]
* [[Claims that Strelka is Rybka]]
* [[Fruit]]
* [[Various Classifications#Mammal|Mammal]]
* [[Rybka]]

=Forum Posts= 
==2007==
* [[http://www.talkchess.com/forum/viewtopic.php?t=13573|New engine from Russia]] by [[Vladimir Medvedev]], [[CCC]], May 05, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=13627|Something 'Fishy' about Strelka]] by [[Dann Corbit]], [[CCC]], May 08, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=13661|Sergei Markow about Strelka]] by Werner Schüle, [[CCC]], May 09, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=13676|To put everything into place with Strelka]] by [[Sergei Markoff]], [[CCC]], May 10, 2007
> [[http://www.talkchess.com/forum/viewtopic.php?t=13676&start=54|Re: To put everything into place with Strelka]] by [[Alexander Schmidt]], [[CCC]], May 11, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=13702|Strelka again]] by [[Sergei Markoff]], [[CCC]], May 11, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=13733|The Strelka affair to date]] by [[Fernando Villegas]], [[CCC]], May 12, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=13716|My review of Strelka Code]] by [[Bryan Hofmann]], [[CCC]], May 12, 2007
* [[http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=1655|Strelka = Rybka 1.0]] by DarkAvenger, [[Computer Chess Forums|Rybka Forum]], July 07, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=14921|Strelka 1.8 UCI released]] by [[Denis Mendoza|Denis P. Mendoza]], [[CCC]], July 07, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=14959|What Strelka tells about Rybka's nodecount and depth]] by [[Ernest Bonnem]], [[CCC]], July 09, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=14988|Longer comments by V. Rajlich]] by [[Marc Lacrosse]], [[CCC]], July 10, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=14995|More proof of Strelka cloning]] by [[Martin Bryant]], [[CCC]], July 10, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=15009|Sensational! Y.Ossipov talking about STRELKA]] by Evgenii Manev, [[CCC]], July 11, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=15017|Strelka and source code experts]] by [[Matthias Gemuh]], [[CCC]], July 11, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=15013|new translation of J.Osipov statement in KasparovChess forum]] by Evgenii Manev, [[CCC]], July 12, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=15076|Fruit, Rybka, Strelka final conclusion! (I hope)]] by [[Michael Sherwin]], [[CCC]], July 13, 2007 » [[Rybka]], [[Strelka]]
* [[http://www.talkchess.com/forum/viewtopic.php?t=16836|Strelka 1.8 source code review]] by [[Bryan Hofmann]], [[CCC]], October 01, 2007
* [[http://www.talkchess.com/forum/viewtopic.php?t=16879|Strelka - clone status]] by [[Dann Corbit]], [[CCC]], October 03, 2007	
* [[http://www.talkchess.com/forum/viewtopic.php?t=18620|Strelka - Open source]] by Evgenii Manev, [[CCC]], December 29, 2007
==2008==
* [[http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=3006|Strelka 2.0]] by [[Vasik Rajlich]], [[Computer Chess Forums|Rybka Forum]], January 11, 2008
* [[http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=3006;pg=4|Re: Strelka 2.0 pg 4]] by [[Anthony Cozzie]], [[Computer Chess Forums|Rybka Forum]], January 11, 2008
* [[http://www.talkchess.com/forum/viewtopic.php?t=18864|What's Strelka's Secret Sauce?]] by [[Steve Maughan]], [[CCC]], January 11, 2008
* [[http://www.talkchess.com/forum/viewtopic.php?t=18885|A comment of Yuri Osipov about V.Rajlich statement]] by Evgenii Manev, [[CCC]], January 12, 2008
* [[http://www.talkchess.com/forum/viewtopic.php?t=18882|ethical dilemma]] by [[Gerd Isenberg]], [[CCC]], January 12, 2008
* [[http://www.talkchess.com/forum/viewtopic.php?t=19008|Rajlich/Osipov/Rybka/Strelka/Answers by Convekta]] by [[Eduard Nemeth]], [[CCC]], January 17, 2008 » [[Rybka]], [[ChessOK|Convekta]]
* [[http://www.talkchess.com/forum/viewtopic.php?t=19316|Toga/Glaurung/Strelka Prunings/Reductions]] by [[Edsel Apostol]], [[CCC]], January 31, 2008 » [[Toga]], [[Glaurung]], [[Pruning]], [[Reductions]]
* [[http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=3172|Anthony Cozzie speak !]] by Silvian, [[Computer Chess Forums|Rybka Forum]], February 03, 2008 <ref>[[http://www.stevelim.com/blog/?p=470|Anthony Cozzie speaks about Rybka source code]] from [[http://www.stevelim.com/|Steve Lim / SuperSteve3d - Home]], February 04, 2008</ref>
* [[http://www.talkchess.com/forum/viewtopic.php?t=20936|Strelka Reverse Engineered from Rybka: Details Examined]] by Rick Fadden, [[CCC]], May 01, 2008
* [[http://www.talkchess.com/forum/viewtopic.php?t=23095|Fruit 2.1 vs Strelka 2.0]] by [[Norman Schmidt]], [[CCC]], August 18, 2008 » [[Fruit]]
* [[http://www.talkchess.com/forum/viewtopic.php?t=23118|Rybka 1.0 vs. Strelka]] by [[Zach Wegner]], [[CCC]], August 19, 2008
* [[http://www.talkchess.com/forum/viewtopic.php?t=23172|counting similiarities between strelka2.0 and fruit2.1]] by [[Uri Blass]], [[CCC]], August 22, 2008
* [[http://www.talkchess.com/forum/viewtopic.php?t=24504|Strelka = Rybka 1.0 =Fruit 2.1 = Toga?? Oh how disappointing]] by [[Oliver Brausch]], [[CCC]], October 21, 2008
==2011==
* [[http://www.talkchess.com/forum/viewtopic.php?t=37762|Fabien's open letter to the community]] by [[Tord Romstad]], [[CCC]], January 23, 2011
* [[http://www.open-chess.org/viewtopic.php?f=3&t=1014|Fabien's open letter to the community]] by [[Tord Romstad]], [[Computer Chess Forums|Open Chess Forum]], January 23, 2011
* [[http://www.open-chess.org/viewtopic.php?f=3&t=1023|Revisiting Strelka/Rybka]] by [[Mark Watkins]], [[Computer Chess Forums|Open Chess Forum]], January 25, 2011
* [[http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=390971&t=37773|Re: Strelka 2.0 B running for the IPON ...]] by [[Jury Osipov]], [[Computer Chess Forums|CCC: Tournaments and Matches]], January 27, 2011
* [[http://www.chessvibes.com/?q=reports/attack-of-the-clones|Attack of the clones | ChessVibes]] by [[David Levy]], 19 February, 2011
* [[http://www.talkchess.com/forum/viewtopic.php?t=40777|Strelka 5 by Yuriy Osipov]] by Slavik Pavloff, [[CCC]], October 15, 2011 » [[Houdini]]
* [[http://talkchess.com/forum/viewtopic.php?topic_view=threads&p=436498&t=41272|Re: Komodo 4 on long time control]] by [[Richard Vida]], [[CCC]], December 04, 2011 » [[Houdini]], [[Komodo]]
==2012 ...==
* [[http://www.talkchess.com/forum/viewtopic.php?t=47144|strelka 5.6]] by [[Don Dailey]], [[CCC]], February 06, 2013 (registration required)
* [[http://www.talkchess.com/forum/viewtopic.php?t=49551|New Strelka 5.7 MP Available...]] by [[Steve Maughan]], [[CCC]], October 02, 2013
* [[http://www.talkchess.com/forum/viewtopic.php?t=52183|Strelka new edition]] by [[Norbert Raimund Leisner]], [[CCC]], May 01, 2014

=External Links=
==Chess Engine==
* [[https://en.wikipedia.org/wiki/Strelka_%28chess_engine%29|Strelka (chess engine) from Wikipedia]]
* [[https://en.wikipedia.org/wiki/Rybka#Strelka_controversy|Strelka controversy from Wikipedia]]
* [[http://strelkachess.narod.ru/|Главная страница]]
* [[http://www.sdchess.ru/Strelka.htm|Strelka Юрия Осипова, Россия]] from [[http://www.sdchess.ru/|sdchess.ru]]
* [[http://www.stevelim.com/blog/?p=470|Anthony Cozzie speaks about Rybka source code]] from [[http://www.stevelim.com/|Steve Lim / SuperSteve3d - Home]], February 04, 2008 » [[Anthony Cozzie]], [[Rybka]] <ref>[[http://rybkaforum.net/cgi-bin/rybkaforum/topic_show.pl?tid=3172|Anthony Cozzie speak !]] by Silvian, [[Computer Chess Forums|Rybka Forum]], February 03, 2008</ref>
* [[http://computerchess.org.uk/ccrl/4040/cgi/engine_details.cgi?print=Details&each_game=1&eng=Strelka%205.5%2064-bit#Strelka_5_5_64-bit|Strelka 5.5 64-bit]] in [[CCRL|CCRL 40/40]]
* [[http://www.chessvibes.com/?q=reports/attack-of-the-clones|Attack of the clones | ChessVibes]] by [[David Levy]], 19 February, 2011
==Misc==
* [[https://en.wikipedia.org/wiki/Strelka|Strelka disambiguation page from Wikipedia]]
* [[https://en.wikipedia.org/wiki/Sputnik_5|Korabl-Sputnik 2 with Belka and Strelka from Wikipedia]]

=References= 
<references />
=What links here?= 
[[include page="Strelka" component="backlinks" limit="100" ]]
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