Rybka

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Rybka, a chess engine by primary author Vasik Rajlich, from 2007 until 2010 dominating and reigning World Computer Chess Champion and holder of the Shannon Trophy, winning the WCCC 2007, WCCC 2008, WCCC 2009 and WCCC 2010, but in June 2011 disqualified by the ICGA from all previous and future World Computer Chess Championships. Rybka further won various IPCCC, Dutch Open Computer Chess Championships, International CSVN Tournaments and on-line tournaments such as CCT Tournaments and ACCA Americas' Computer Chess Championships. Rybka is a standalone chess engine supporting the UCI protocol.

=Team= The Rybka team consists of primary author and International Master Vasik Rajlich, supported by Grandmaster and evaluation expert Larry Kaufman (Rybka 3), Rybka's main tester and Women's GM (WGM) and IM Iweta Rajlich, the opening book authors Jeroen Noomen, Dagh Nielsen, Jiří Dufek and Nick Carlin, as well as Rybka primary tournament operator Hans van der Zijden, hardware expert Lukas Cimiotti and Webmaster and Webdesigner Felix and Christoph Kling.

=Versions= Vasik Rajlich started developing Rybka in about 2003, and worked full-time on it since 2005. The appearance of the free Rybka 1 beta and the first commercial version, Rybka 1 end of 2005 was a sensation, and Rybka soon became the dominating program leading rating lists by a huge margin. Rybka 3 was developed in collaboration with Larry Kaufman, the most recent and strongest version Rybka 4 and the parallel version Deep Rybka 4 appeared in April 2010, market as standalone chess engine from RybkaChess.com, from ChessOK optional with the Aquarium GUI , or from ChessBase packaged with the Fritz GUI. The demo version Rybka 2.3.2a can be downloaded for free.

=Achievements=

=Program Internals= Rybka is a bitboard engine, first versions rotated, Rybka 4 apparently magic bitboards for sliding piece attack and move generation. Vasik once posted a snippet of Rybka source-code, a typical bitboard serialization loop to generate white knight captures. for (bb_t knights = Board.pieces [WN]; knights; knights &= knights-1) {   int knight_sq = bit_scan (knights); for (bb_t captures = knight_moves [knight_sq] & opponent_pieces; captures; captures &= captures - 1) {       int capture_sq = bit_scan (captures); *moves ++ = move (knight_sq, capture_sq); *values++ = Board.sq [capture_sq] * 256 + 192; } } Due to the disputed open source engines Strelka 2.0 and later Ippolit, which accordant to Vasik Rajlich were both based on or heavily influenced by re-engineered Rybka executables, other implementation details were released to the public, such as material- and material imbalance tables, aggressive LMR, razoring and some variation of singular extensions. Zach Wegner elaborated on evaluation issues, and compared Rybka 1 beta with Fruit's evaluation, continued by former anonymous author "BB+" alias Mark Watkins in February 2011.

=Release Dates=
 * Rybka 1.0 beta : 2005-12
 * Rybka 1.0 :
 * Rybka 1.1 : 2006-04
 * Rybka 1.2 : 2006-06
 * Rybka 1.5 :
 * Rybka 1.6.1 :
 * Rybka 2.0 :
 * Rybka 2.2 : 2006
 * Rybka 2.2n2 : 2006-12
 * Rybka 2.3 : 2007-01
 * Rybka 2.3.1 : 2007-02
 * Rybka 2.3.2a : 2007-06
 * Rybka 3 : 2008-08
 * Rybka 4 : 2010-05
 * Rybka 4.1 : 2011-3

=Controversies=

Rybka 1.0 and Fruit
Rajlich's interpretation of nodes and depth   , and the controversy about Strelka  raised suspicions about the initial origin of Rybka 1.0  , but Vasik Rajlich categorically denied Rybka 1.0 was based on Fruit  , as initially confirmed by Chrilly Donninger in 2005 after early rumors and questions arose, but despite confusing Fruit using MTD(f), Donninger claimed Rybka was basically Fruit in 2007.

Vasik Rajlich's most quoted statement in these discussions was probably from an interview in uciengines.de, December 20, 2005 : Yes, the publication of Fruit 2.1 was huge. Look at how many engines took a massive jump in its wake: Rybka, Hiarcs, Fritz, Zappa, Spike, List, and so on. I went through the Fruit 2.1 source code forwards and backwards and took many things. ... Anyway, if I really had to give a number - my wild guess is that Rybka would be 20 rating points weaker had Fruit not appeared.

Ippolit
The appearance of the Ippolit open source program by pseudonymous authors in May 2009, and Rajlich's claim it is a clone of Rybka 3 without any substantiation and evidence, caused further discussions.

Open Letters
In January 2011, Fabien Letouzey confirmed that Strelka, the allegedly clone of Rybka, was not a verbatim copy of the source code from Fruit, but a bitboard re-write of Fruit with some other ideas, and not just an extraction of a couple of ideas.

On February 19, 2011 ICGA president David Levy broached on cloning issues in a ChessVibes column. In March 2011, following computer chess programmers signed an open letter to David Levy, Jaap van den Herik and the board of the ICGA, to support the claim Rybka 1.0 beta and subsequent versions were allegedly derivatives from Fabien Letouzey’s program Fruit 2.1:
 * Fabien Letouzey
 * Zach Wegner
 * Mark Uniacke
 * Stefan Meyer-Kahlen
 * Ed Schröder
 * Don Dailey
 * Christophe Théron
 * Richard Pijl
 * Amir Ban
 * Anthony Cozzie
 * Tord Romstad
 * Ralf Schäfer
 * Gerd Isenberg
 * Johannes Zwanzger
 * Shay Bushinsky
 * Volker Böhm

The letter was published in the private ICGA Investigations Wiki and elsewhere. The German sites Heise online and Spiegel Online broached the issue.

=Pre-Beta Rybka and Crafty= In February and March 2011, evidence was found by Zach Wegner and Mark Watkins that pre-Beta Rybka, which played the CCT6 in January 2004, and competed in tournaments of Engine Rating Lists such as ChessWar and Le Fou numérique, contain a substantial amount of Crafty code , confirmed by Robert Hyatt. Beside other evidence there are the known bugs in the old Crafty code (if ms == 99999) that caused El Chinito by primary author Eugenio Castillo Jiménez to be exposed as a clone. =Disqualification= In June 2011, the ICGA has disqualified and banned Rybka and its programmer Vasik Rajlich from previous and future World Computer Chess Championships. The ICGA accuses Rajlich of plagiarizing two other programs, Crafty and Fruit, and demands that he returns the trophies and prize money of the World Computer Chess Championships in 2007, 2008, 2009 and 2010.

In August 2011, the board of the Dutch Computer Chess Federation (CSVN) declared the most serious doubts as to the rightfulness of ICGA's decision. Therefore, they have chosen not to abide by their sanctions against Rybka, see ICGA Investigations

=See also=
 * Claims that Strelka is Rybka
 * Crafty
 * Fritz
 * Fruit
 * ICGA Investigations
 * Ippolit
 * Rybka Controversy
 * Strelka

=Publications=
 * Jeroen Noomen, Jos Uiterwijk, Jaap van den Herik (2007). The 15th World Computer Chess Championship. ICGA Journal, Vol. 30, No. 2 » WCCC 2007
 * Matej Guid, Ivan Bratko (2007). Factors affecting diminishing returns for searching deeper. CGW 2007 » Crafty, Rybka, Shredder, Diminishing Returns
 * Matej Guid, Ivan Bratko (2007). Factors affecting diminishing returns for searching deeper. ICGA Journal, Vol. 30, No. 2, pdf
 * Hans Secelle. Eric van Reem (2007). Golden Summer for RYBKA. ICGA Journal, Vol. 30, No. 3
 * Mark Watkins (2010). A comparison of Rybka and IPPOLIT. pdf » Ippolit
 * Mark Watkins (2011). A comparison of Rybka 1.0 Beta and Fruit 2.1, pdf, February 12, 2011 Version
 * Mark Watkins (2011). A comparison of Rybka 1.0 Beta and Fruit 2.1, pdf, February 24, 2011 Version
 * Mark Watkins (2011). A comparison of Rybka 1.0 Beta and Fruit 2.1, pdf, March 11, 2011 Version » Fruit
 * Anthony Cozzie (2011). The Future of Computer Chess. Selective Search 154, pp. 11, pdf hosted by Mike Watters
 * Jaap van den Herik, Krzysztof Siewicz (2011). Open Source has a Price. ICGA Journal, Vol. 34, No. 2
 * David Levy (2011). Rybka Disqualified and Banned from World Computer Chess Championships.ICGA Journal, Vol. 34, No. 2
 * David Levy (2011). A Very Sad Case. ICGA Journal, Vol. 34, No. 2
 * Mark Lefler, Robert Hyatt, Harvey Williamson, ICGA panel (2011). Rybka Investigations and Survey of Findings for the ICGA. ICGA Journal, Vol. 34, No. 2
 * Eric Hallsworth (2011). Rybka disqualified and banned by ICGA from World Computer Chess Championships, Lifetime Ban for Vasik Rajlich. Selective Search 155, pp. 8, pdf hosted by Mike Watters
 * Mark Watkins (2011). Review of the Rybka case. pdf from OpenChess Forum
 * Søren Riis (2012). A Gross Miscarriage of Justice in Computer Chess. pdf hosted by ChessBase
 * Arno Nickel (2012). Die schöne neue Welt der Schachengines. SCHACH 2,3,5,6 2012, pdf (German)
 * Ed Schröder (2012). Rybka reloaded. pdf
 * Matej Guid, Ivan Bratko (2012). Detecting Fortresses in Chess. Elektrotehniški vestnik, Vol. 79, Nos. 1-2, pdf » Houdini
 * Mark Watkins (2013). Review of the Rybka case. pdf
 * Søren Riis (2014). What makes a chess program original? Revisiting the Rybka case. Entertainment Computing, Vol. 5, No. 3
 * Don Dailey, Adam Hair, Mark Watkins (2014). Move Similarity Analysis in Chess Programs. Entertainment Computing, Vol. 5, No. 3, preprint as pdf
 * David Levy (2014). The RYBKA Case – Progress and Verdict. ICGA Journal, Vol. 37, No. 4 » Rybka Controversy

=Forum Posts=

2004

 * Re: CCT6: Rybka /Bodo ??? by Vasik Rajlich, CCC, January 27, 2004

2005

 * Rybka 1.0 beta release - need testers by Vasik Rajlich, CCC, November 30, 2005
 * Rybka 1.0 Announcement by Vasik Rajlich, CCC, December 05, 2005
 * Is Rybbka a fruit clone? by Ziad Haddad, CCC, December 06, 2005
 * Rybka - How much Fruit is inside? by Daniel Mehrmann, CCC, December 11, 2005
 * Rybka test position by K. Burcham, CCC, December 11, 2005 » Ktulu
 * Rybka uses PVS and not MTD(f). Its no Fruit-Clone by Chrilly Donninger, CCC, December 12, 2005
 * The Code for the Rybka-Mate-Bug by Chrilly Donninger, CCC, December 13, 2005
 * Unmasking the Secrets of Rybka and Fruit by Stuart Cracraft, CCC, December 15, 2005
 * Secrets of Rybka and Fruit from my point of view by Sergei S. Markoff, CCC, December 15, 2005
 * Spike-Rybka by Vasik Rajlich, CCC, December 28, 2005 » IPCCC 2005 b
 * The man behind Rybka and his thoughts as posted here on CCC by Mike Byrne, CCC, December 31, 2005

2006

 * Rybka and Fruit on Chessbase by Walter Faxon, CCC, January 14, 2006 » Fruit, ChessBase
 * The superior Rybka chess knowledge by Chrilly Donninger, CCC, January 18, 2006
 * Rybka's NPS - one presumption by Vladan Vučković, CCC, February 16, 2006 » Nodes per Second
 * Rybka @ CCT8 by Vasik Rajlich, CCC, February 26, 2006

2007

 * outlook and plans for Rybka 3 by Vasik Rajlich, Rybka Forum, January 09, 2007
 * Rybka 2.3 release date now Monday February 12 by Vasik Rajlich, Rybka Forum, February 04, 2007
 * Rybka 2.3 readme by Vasik Rajlich, Rybka Forum, February 13, 2007
 * Rybka @ Leiden ICT7 by Vasik Rajlich, Rybka Forum, May 20, 2007
 * Open Letter and $100,000 Challenge to FIDE by Vasik Rajlich, Rybka Forum, May 31, 2007
 * How secure is the source code of Rybka? by SR, Rybka Forum, June 05, 2007
 * Rybka 2.3.2a readme by Vasik Rajlich, Rybka Forum, June 18, 2007
 * Rybka @ Amsterdam 15th WCCC by Vasik Rajlich, Rybka Forum, June 19, 2007
 * Strelka = Rybka 1.0 by DarkAvenger, Rybka Forum, July 07, 2007 » Strelka
 * 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
 * (Experimental) 64-bit Rybka on Linux by Sesse, Rybka Forum, July 10, 2007 » Linux
 * Re: Is Rybka a derivative of Fruit? by Vasik Rajlich, Rybka Forum, July 14, 2007
 * Fruit, Rybka, Strelka final conclusion! (I hope) by Michael Sherwin, CCC, July 13, 2007
 * Rybka vs Zappa in Mexico City by Vasik Rajlich, Rybka Forum, September 28, 2007
 * Re: I know something of Dr.Donninger by Harvey Williamson, Hiarcs Forum, October 16, 2007
 * Rybka @ Leiden 27th Dutch CCC by Vasik Rajlich, Rybka Forum, October 29, 2007

2008

 * Strelka 2.0 by Vasik Rajlich, Rybka Forum, January 11, 2008 » Strelka
 * Re: Strelka 2.0 pg 4 by Anthony Cozzie, Rybka Forum, January 11, 2008
 * Rajlich/Osipov/Rybka/Strelka/Answers by Convekta by Eduard Nemeth, CCC, January 17, 2008 » Strelka, Convekta
 * Anthony Cozzie speak ! by Silvian, Rybka Forum, February 03, 2008
 * Rybka 3 with new GUI: are they serious?! by Jouni Uski, CCC, April 05, 2008 » Aquarium
 * Retry: Rybka 1.0 Beta Node Count Patch by Rick Fadden, CCC, April 19, 2008
 * Strelka Reverse Engineered from Rybka: Details Examined by Rick Fadden, CCC, May 01, 2008
 * Rybka @ Leiden 8th ICT by Vasik Rajlich, Rybka Forum, June 01, 2008
 * Rybka 3 -- a hundred elo! by Larry Kaufman, Rybka Forum, July 08, 2008
 * Rybka 3 - some info by Vasik Rajlich, Rybka Forum, July 19, 2008
 * Rybka 3: The dark truth behind the hype by Albert Silver, CCC, July 25, 2008
 * Rybka 3 Release Notes by Vasik Rajlich, Rybka Forum, August 04, 2008
 * Rybka 3 FAQ by Vasik Rajlich, Rybka Forum, August 05, 2008
 * Rybka v2.2n2 download by Vasik Rajlich, Rybka Forum, August 06, 2008
 * Rybka 1.0 vs. Strelka by Zach Wegner, CCC, August 19, 2008
 * Rybka in the nolot suite by Uri Blass, CCC, August 21, 2008 » The Nolot Suite
 * Questions for Vas by Zach Wegner, CCC, August 25, 2008
 * A very simple question to Vas that can end it all by Christophe Théron, CCC, August 25, 2008
 * Rybka questions and answers by Chris Whittington, CCC, August 25, 2008
 * question to vas on similarity of rybka 1.0 to fruit by duncan, Rybka Forum, August 25, 2008
 * split 3 from Zach technical thread by Christophe Théron, CCC, August 27, 2008
 * My two cents by Anthony Cozzie, CCC, August 27, 2008
 * To campaign or not by Ed Schroder, CCC, August 28, 2008
 * How a court detects a derivative work by Christophe Théron, CCC, August 30, 2008
 * Is It Me or is the Source Comparison Page Rigged? by RegicideX, CCC, September 01, 2008
 * Plagiarism and Rybka by Enrique Irazoqui, CCC, September 03, 2008
 * Rybka @ 16th WCCC in Beijing by Vasik Rajlich, Rybka Forum, October 04, 2008
 * Strelka = Rybka 1.0 =Fruit 2.1 = Toga?? Oh how disappointing by Oliver Brausch, CCC, October 21, 2008
 * Rybka @ 28th Dutch CCC by Vasik Rajlich, Rybka Forum, November 18, 2008

2009

 * Rybka @ Pamplona 17th ICGA World Computer Chess Championship by Vasik Rajlich from Rybka Forum, May 17, 2009 » WCCC 2009
 * Rybka @ 29th Open Dutch Computer Chess Championship by Vasik Rajlich, Rybka Forum, October 19, 2009 » DOCCC 2009
 * Official statement on [Deleted?] by Vasik Rajlich, Rybka Forum, October 21, 2009

2010

 * Rybka 4 update by Vasik Rajlich, Rybka Forum, April 11, 2010
 * Rybka 4 is final. (select games for fun) by Albert Silver, CCC, May 25, 2010
 * Rybka 4 Release Notes by Vasik Rajlich, Rybka Forum, May 26, 2010
 * ICT Leiden 2010: Rybka wins with 8/9. Opening report by Jeroen Noomen, Rybka Forum, May 30, 2010 » ICT 2010
 * Rybka @ 10th ICT Leiden 2010 by Vasik Rajlich, Rybka Forum, May 31, 2010 » ICT 2010
 * BB's Rybka/Ippolit comparison by Zach Wegner, OpenChess Forum, June 13, 2010
 * Deep Blue vs Rybka by Don Dailey, CCC, September 13, 2010
 * Kanazawa Diary (Rybka operator in Japan) by Hans van der Zijden, Rybka Forum, September 24, 2010 » WCCC 2010
 * WCCC 2010 in Kanzawa, Japan by Vasik Rajlich, Rybka Forum, October 2, 2010 » WCCC 2010
 * Rybka @ 30th Dutch Computer Chess Championship by Vasik Rajlich, Rybka Forum, November 16, 2010 » DOCCC 2010
 * Brief Q&A about Rybka 1.0 Beta and Fruit 2.1 by BB+, OpenChess Forum, December 14, 2010
 * Rybka Cluster Rental Program by Vasik Rajlich, Rybka Forum, December 30, 2010

2011

 * Node counting by BB+, OpenChess Forum, January 20, 2011 » Node
 * Fabien's open letter to the community by Tord Romstad, CCC, January 23, 2011
 * Fabien's open letter to the community by Tord Romstad, OpenChess Forum, January 23, 2011
 * Revisiting Strelka/Rybka by BB+, OpenChess Forum, January 25, 2011
 * Feb 12 version: Rybka 1.0 Beta / Fruit 2.1 document by BB+, OpenChess Forum, February 12, 2011
 * Attack of the clones | ChessVibes by David Levy, February 19, 2011 (Wayback Machine)
 * Open letter to the ICGA about the Rybka-Fruit issue by Harvey Williamson, Hiarcs Forum, March 01, 2011
 * Programmers Open Letter to ICGA on Rybka/Fruit by BB+, OpenChess Forum, March 01, 2011
 * Rybka 1.6.1 by Robert Hyatt, Rybka Forum, March 13, 2011
 * Longer Article by Anthony Cozzie, CCC, March 17, 2011
 * History of eval changes in Rybka versions byBB+, OpenChess Forum, March 23, 2011
 * Rybka disqualified and banned from World Computer Chess Cham by Tim Chan, CCC, June 29, 2011
 * Rybka disqualified and banned from World Computer Chess Cham by TheHug, Rybka Forum, June 29, 2011
 * Rybka disqualified and banned from WCCC by Harvey Williamson, Hiarcs Forum, June 29, 2011
 * Rybka disqualified and banned from WCCC by Jeremy Bernstein, OpenChess Forum, June 29, 2011
 * Rybka ban thoughts by Dann Corbit, CCC, June 29, 2011
 * My two cents on Rybka's disqualification by Joona Kiiski, CCC, June 30, 2011
 * Dismissed with prejudice by Dann Corbit, CCC, July 01, 2011
 * Voir Dire by Dann Corbit, CCC, July 01, 2011
 * Vas say something by siam, Rybka Forum, July 01, 2011
 * The ICGA Process by BB+, OpenChess Forum, July 01, 2011
 * Progess (often) is ugly, a summary try by Rebel, OpenChess Forum, July 03, 2011
 * Is Rybka that needs ICGA or the opposite ? by Marco Costalba, CCC, July 03, 2011
 * The Intellectual Property Oxymoron by Gary Belton, CCC, July 03, 2011
 * The Evidence against Rybka by BB+, OpenChess Forum, July 04, 2011
 * Why did the ICGA ignore this advice? by John Sidles, Rybka Forum, July 06, 2011
 * Minority Report Plagiarism - Quantifying Evaluation Features by Trotsky, Rybka Forum, July 09, 2011
 * Back to R3/IPPOLIT(/R4?) by BB+, OpenChess Forum, July 14, 2011
 * In retrospect by Rebel, Rybka Forum, July 14, 2011
 * Minority Report 2 - Unravelling the technical report by Trotsky, Rybka Forum, July 22, 2011
 * Minority Report 3, PST + other lookup tables are they legal? by Trotsky, Rybka Forum, July 25, 2011
 * On Rybka/Crafty and licensing/copyright by BB+, OpenChess Forum, July 28, 2011
 * Thoughts on Fruit=Rybka EVAL by Rebel, OpenChess Forum, August 16, 2011
 * Apology to Vas by Rebel, Rybka Forum, August 17, 2011

2012

 * Rybka evidence recapitulation by BB+, OpenChess Forum, January 03, 2012
 * A Big Thanks and a Small Update by Vasik Rajlich, Rybka Forum, January 08, 2012
 * Fruit/Rybka timeline by BB+, OpenChess Forum, January 09, 2012
 * Rybka 1.0 source code by Ed Schröder, CCC, January 31, 2012

2021

 * Rybka Forum Is Officially Closed? by supersharp77, CCC, September 02, 2021

=External Links=

Rybka

 * Welcome to RybkaChess.com!
 * Rybka Cluster - for the elite chess player
 * Rybka from Wikipedia
 * Rybka's ICGA Tournaments
 * Rybka Chess Community Forum
 * Interview with Vasik Rajlich by Christopher Conkie, Michael Diosi, Frank Quisinsky & Alexander Schmidt, December 20, 2005, hosted by Ed Schröder
 * ChessAssistance.com Rybka Review by Robert Pawlak, September 23, 2006
 * Rybka 3.0 – Not just the strongest chess program in the world, July 18, 2008, ChessBase News
 * Rybka's Monte Carlo analysis by Steve Lopez, ChessBase News, February 03, 2009

Controversy

 * Rybka banned by International Games Federation – Rybka Ruling
 * Rybka, the world’s best chess engine, outlawed and disqualified | ExtremeTech by Sebastian Anthony on June 29, 2011
 * Computer chess champ stripped of its four titles by Claire Courchane, Washington Times, June 30, 2011
 * Rybka Disqualified, Banned On Plagiarism Charges | ITProPortal.com by Ravi Mandalia, June 30, 2011
 * Boylston Chess Club Weblog: Rybka banned from computer champs; stripped of all its titles, June 30, 2011
 * Weltmeisterprogramm Rybka verliert alle Titel by Frank Patalong, Spiegel Online, July 01, 2011 (German)
 * Geklontes Fischchen by Stefan Löffler, July 08, 2011, DiePresse.com (German)
 * Rybka vs ICGA a different view by Ed Schröder, November 09, 2011
 * Rybka evidence by Ed Schröder, November 09, 2011
 * A Gross Miscarriage of Justice in Computer Chess (part one) by Søren Riis, ChessBase News, January 02, 2012
 * A Gross Miscarriage of Justice in Computer Chess (part two) by Søren Riis, ChessBase News, January 03, 2012
 * A Gross Miscarriage of Justice in Computer Chess (part three) by Søren Riis, ChessBase News, January 04, 2012
 * A Gross Miscarriage of Justice in Computer Chess (part four) by Søren Riis, ChessBase News, January 05, 2012


 * ICGA/Rybka controversy: An interview with David Levy (1), ChessBase News, February 06, 2012
 * ICGA/Rybka controversy: An interview with David Levy (2), ChessBase News, February 10, 2012


 * ICGA/Rybka controversy: Feedback, ChessBase News, February 17, 2012

Misc

 * Rybka (disambiguation) from Wikipedia

=References= Up one Level