Rybka Controversy

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Allegations have surfaced that Rybka 1.0 beta and other versions of Rybka are derivatives of Fruit 2.1 and Crafty. If versions of Rybka are derived from Fruit and participated in ICGA tournaments, then Rybka has violated ICGA Tournament Rules. Fruit 2.1 source code was distributed with a specific license. Part of this license reads "For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights." Allegations state that by distributing Rybka which is based on Fruit, this GNU license was violated. The ICGA rules state "Programming teams whose code is derived from or including game-playing code written by others must name all other authors, or the source of such code, in the details of their submission form.". No such notification was included in the Rybka entry forms.

=Timeline=

Wegner
Zach Wegner analyzed the Rybka 1.0 beta exe file and noted many similarities in the two program's evaluation functions:
 * [[File:ZW_Rybka_Fruit.pdf]]

Letouzey
On Jan 23, 2011, Fabien Letouzey, author of Fruit, sent a letter to Tord Romstad about Strelka and Rybka
 * Copy of the letter

Watkins
Mark Watkins also analysed Rybka 1.0 beta and details even more similarities:
 * [[File:RYBKA_FRUIT_Mar11.pdf]]
 * Annotated version of 64-bit evaluation function:
 * [[File:R1x64eval.txt]]

Levy
On February 19, 2011 ICGA president David Levy broached on cloning issues in a ChessVibes column.

Programmers
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-History of Rybka=

2003
About March or April 2003, Rajlich starts work on Rybka (see interview by Nelson Hernandez).

2004
In January, Rybka competed in CCT6, the largest online author-based tournament (a posting of Rajlich's from time gives a "Rybka 1.3" as a version number). In April, Rybka 1.5 enters the privately-run author-based tournaments Chess War V and Le Systeme du Saison. In October(?), Rybka 1.6 enters Chess War VI and AEGT 3. Rybka 1.6 also competed in Chess War VII.

There is ample evidence that the latter two versions contained large amounts of Crafty code, in direct contravention of both the relevant Crafty license and the rules of these tournaments. Based on the last tournament pre-Rybka played in, its rating was about 2064 ELO.

Fruit 2.1
Fruit 2.1 was released in June 2005. For the purposes of prima facie evidence, it is necessary to establish that Rajlich obtained a copy. This can be inferred from his own words: I went through the Fruit 2.1 source code forwards and backwards and took many things.

=History of Rybka 1.0 and beyond=

2005

 * Rybka 1.0 Beta is released Dec 5 as a free download, and after a week the "Rybka 1" series becomes available on a subscription basis. About 13 "beta" versions of Rybka 1.0.1 were released over the next few months. Rybka 1.0.1-Beta-(x)? competed (as Rybka beta) and won first place in Paderborn (December 27 2005).
 * The first commercial version, Rybka 1 end of 2005.

2006

 * On June 10 (date from RybkaChess FAQ about Rybka 2.x), the MP-only Rybka 2.0 Beta is released. The date on various executables are Apr 23 (Beta 8) and May 17 (Beta 4).
 * Rybka (under the name Rajlich) competed in the 2006 ICGA Chess Tournament
 * Rybka 2.1 was released Jul 26, 2006.
 * Rybka 2.2 was released Nov 10, 2006.
 * Rybka 2.2n2 was released Dec 14, 2006. All these dates are from the RybkaChess FAQ about Rybka 2.x (though that page seems to disappear every now and then).

2007

 * Rybka 2.3 was released in late Feb 2007 (?). There was an "LK" version that had minor differences.
 * A few more "2.3.1 beta" versions also appeared around this time (again including Kaufman's latest material imbalance numbers). The Rybka 2.3 evaluation function appears to retain the numerology from Rybka 1.0 Beta. Rybka 2.3.1 starts to make a few changes (due to Kaufman?) in the numbers, though keeping the structure largely intact.
 * Rybka 2.3.2 was released Jun 13, 2007, and 2.3.2a about 5 days later.

Won ICGA Tournaments

 * 15th World Computer Chess Championship - Amsterdam 2007 (ICGA Tournaments) » WCCC 2007
 * 16th World Computer Chess Championship - Beijing 2008 (ICGA Tournaments) » WCCC 2008
 * 17th World Computer Chess Championship - Pamplona 2009 (ICGA Tournaments) » WCCC 2009
 * WCCC 2010

Later Rybkas
There is still investigation to be done concerning what was in these later Rybkas. The evaluation function in Rybka 2.3 (late Feb 2007, as above) looks to be that of Rybka 1.0 Beta (the executable contains many variants of the eval function, which seem to be either obfuscation or optimisation -- for instance, rook eval is dropped in one, so maybe if there are no rooks on the root position, this path would be taken). Here is a raw dump of the eval, with annotations to be added :
 * [[file:R230eval.txt]]

Evaluation
Here is my list of differences in eval between Rybka 2.3 (mid Feb 2007) and Rybka 1.0 Beta. As with some other Rybka versions, there are multiple "versions" of the eval function (e.g., some might ignore rooks) which might be due to some sort of optimisations (e.g. no rooks in root position).


 * The 1-3-5-10 material weighting is multiplied by 3717 rather than 3399.
 * The material imbalance adjustments are slightly perturbed. It seems that Rybka 2.2mp (Oct 31 2006) still had the same material imbalances as Rybka 1.0 Beta, but 2.2n2 (Dec 2 2006) differed (this version also is the first I can find to have 3717 rather than 3399).
 * lazy eval has some sort of "positional evaluation" incrementation (likely changed fairly early in the Rybka series).
 * The 3-centipawn tempo bonus was removed (not sure when - Rybka 2.1o had a 10-centipawn bonus, in some eval funcs).
 * PawnFile PST is now [-4,-1,0,+1,+1,0,-1,-4] rather than -3 on a/h files.
 * Drawishness from pawn files was added (already in Rybka 1.2, maybe earlier).
 * The opening/endgame interpolation is now linear.

Everything else (including numerology and computation methods) seems the same in Rybka 2.3 and Rybka 1.0 Beta. There are minor differences in the SWAR-based popcnt method, which could be just a different choice of compiler. Similarly, part of the mobility computations with lazy-eval seems to be inlined.

I think it is safe to say that very little work was done on the Rybka eval from Dec 2005 to somewhere around late 2006 or early 2007 (when Kaufman was hired).


 * The evaluation function of Rybka 2.3.2a contains a few modifications, presumably due to Kaufman. Partially annotated version of Rybka 2.3.2a 64-bit evaluation function
 * [[file:Ryb232eval.txt]]


 * This document aligns the evaluations of Rybka 1.0 beta and Rybka 2.3.2a, showing nearly identical evaluation features (with some minor additions and tunings to 2.3.2a):
 * [[file:RybkaEvalCompare.pdf]]


 * Here is the "iterative deepening" part of the root search in Rybka 2.3.2a, to be compared to latter half of the function (starting with the easy move check) in Appendix A of the PDF:
 * [[file:Ryb232a.iter.txt]]

Comparisons with other Engines
A detailed comparison of Rybka 1.0 and 2.3.2a versus other chess engines shows about a 1 in 10^12 or more chance of evaluation overlap occurring "randomly"

=Claims and Evidence=
 * Claims of Rybka Originality
 * Claims that Strelka is Rybka
 * Pre-Fruit Rybka and Crafty
 * Rybka-Crafty Evidence - re-use of code to tablebase use in KP vs KP when en passant was possible
 * Rybka-Crafty Evidence II - checking whether the return value of EvaluateMate was 99999
 * Rybka-Crafty Evidence III - repeated zeroing of an element in a pawn hash structure
 * Rybka-Crafty Evidence IV - the first part of the Evaluation functions
 * Rybka-Crafty Evidence V - the EvaluateWinner function
 * Rybka-Crafty Evidence VI - NextMove and NextEvasions functions

=Summary Report= The Summary Report on the Rybka Controversy prepared by the secretariat, can be found here:

This report has been sent by David Levy to Vasik Rajlich, asking him to provide comments. Panel members are reminded to keep this report private to allow Vasik Rajlich a chance to respond. It is expected sometime in the future this summary will be made public.

Note from the Summary Report concerning Rybka 3 Evaluation co-developer Larry Kaufman: =Decision concerning Rybka= The final decision on the Rybka case by the ICGA Board, June 28, 2011: Rybka disqualified and banned from World Computer Chess Championships.

Rybka Disqualified and Banned from World Computer Chess Championships

The International Computer Games Association (ICGA) has been conducting an investigation into allegations that, in the chess program Rybka, the programmer Vasik Rajlich plagiarized two other programs: Crafty and Fruit. The ICGA has considered and evaluated the evidence presented to the investigation panel and the report prepared by the panel’s Secretariat. (The report and evidence files are attached.) We would like to thank those members of the panel who contributed to this investigation and the Secretariat for the enormous amount of conscientious work they have put in to this matter.

By a unanimous 5-0 decision of executive members of the ICGA we find ourselves in agreement with the verdict of the Secretariat’s report. We are convinced that the evidence against Vasik Rajlich is both overwhelming in its volume and beyond reasonable question in its nature. Vasik Rajlich is guilty of plagiarizing the programs Crafty and Fruit, and has violated the ICGA’s tournament rules with respect to the World Computer Chess Championships in the years 2006, 2007, 2008, 2009 and 2010. Specifically, Vasik Rajlich, on all five occasions, violated Tournament Rule 2 which requires that:

By claiming other programmers’ work as his own, and failing to comply with the above mentioned rule, Vasik Rajlich has unfairly been awarded one shared 2nd-3rd place (in 2006) and four World Computer Chess Championship titles (in 2007, 2008, 2009 and 2010). Furthermore, it seems to the ICGA that Vasik Rajlich clearly knew that he was in the wrong in doing so, since he has repeatedly denied plagiarizing the work of other programmers.

The ICGA regards Vasik Rajlich’s violation of the above mentioned rule as the most serious offence that a chess programmer and ICGA member can commit with respect to his peers and to the ICGA. During the course of the investigation and upon presentation of the Secretariat’s report Vasik Rajlich did not offer, despite repeated invitations from the ICGA to do so, any kind of defence to the allegations, or to the evidence, or to the Secretariat’s report, other than to claim in an e-mail to myself on May 13th 2011 that:
 * Rybka has does not “include game-playing code written by others”, aside from standard exceptions which wouldn’t count as ‘game-playing’.
 * The vague phrase “derived from game-playing code written by others” also does not in my view apply to Rybka.

The ICGA is of the view that such a serious offence deserves to be met with correspondingly serious sanctions against the perpetrator. In deciding on appropriate sanctions the ICGA has borne in mind the approach of the International Olympic Committee for dealing with the most serious cases of the violations of its rules.

The ICGA has therefore decided as follows:


 * Vasik Rajlich is hereby disqualified from the World Computer Chess Championships (WCCC) of 2006, 2007, 2008, 2009 and 2010.
 * The 2nd-3rd place awarded to the program called “Rajlich” in the 2006 WCCC is hereby annulled, sole 2nd place is awarded to the program Shredder, and 3rd place in that event is awarded to the program Zappa.
 * The 1st places and World Computer Chess Champion titles awarded to the program Rybka in the 2007, 2008, 2009 and 2010 WCCCs are hereby annulled, and all the other programs that competed in those events are moved up in the final tournament standings by one place. Thus the revised tournament standings and titles for those events will now be as follows.

2007

 * 1st Zappa (World Champion)
 * 2nd Loop
 * =3rd GridChess
 * =3rd Shredder

2008

 * 1st Hiarcs (World Champion)
 * 2nd Junior
 * 3rd Cluster Toga

2009

 * =1st Junior (Joint World Champion)
 * =1st Shredder (Joint World Champion)
 * =1st Deep Sjeng (Joint World Champion)

2010

 * =1st Rondo (Joint World Champion)
 * =1st Thinker (Joint World Champion)
 * 3rd Shredder

In due course those programmers whose programs have been elevated to World Champion (or joint World Champion) status will receive from the ICGA replicas of the Shannon trophy for the appropriate years.

The plaques on the Shannon trophy that currently bear the name Rybka (for the years 2007-2010) will be removed from the trophy and new plaques will be engraved with the names of the revised winners of the title.

Similarly, the titles of World Computer Speed (Blitz) Chess Champion that were awarded to Rybka in 2009 and 2010 are hereby annulled. The revised winners of the speed chess title for those years are therefore:
 * 2009 Shredder
 * 2010 Jonny and Shredder (joint champions)

Vasik Rajlich is banned for life from competing in the World Computer Chess Championship or any other event organized by or sanctioned by the ICGA.

The ICGA demands that Vasik Rajlich return to the ICGA the four replicas of the Shannon Trophy presented at the World Computer Chess Championships in 2007, 2008, 2009 and 2010, and to return to the ICGA all prize money awarded for Rybka’s performances in those events.

David Levy [President - ICGA] June 28th 2011

=Aftermath= After the ICGA decision, heated forum discussions arose. Chris Whittington and Ed Schröder et al. criticize the ICGA investigation process, the work of the panel, and the ICGA decision. Sven Schüle, Miguel A. Ballicora , Chris Whittington , Richard Vida , Mark Watkins  and others elaborate and discuss Piece-Square Table matters.

CSVN Decision
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 :

Open Letter
At September 21, 2001, 15 former participants (14 program authors), Amir Ban, Don Dailey, Robert Hyatt, Gerd Isenberg, Marcel van Kervinck, Stefan Meyer-Kahlen, Fabien Letouzey, Thomas Mayer, Daniel Mehrmann, Gian-Carlo Pascutto, Richard Pijl, Ralf Schäfer, Mark Uniacke, Ben-Hur Carlos Vieira Langoni Júnior, and Harvey Williamson signed an open letter to the CSVN and its board - to protest against their decision to ignore the ICGA suggestion and to allow Rybka playing their tournaments, the Dutch Open Computer Chess Championship and the International CSVN Tournament, and declared they will no longer enter these tournaments under the current CSVN direction.

Different Views
In November 2011, Ed Schröder announced his new web-sites summarizing his alternative view of the historic ICGA - RYBKA event that led to the ban of Rybka and Vasik Rajlich. Short later, in January 2012, ChessBase, a Rybka distributer, took a stand, publishing an article series in four parts by Danish mathematician and Rybka Forum moderator Søren Riis on their site - A Gross Miscarriage of Justice in Computer Chess, also published as pdf.

Litmus Test?
Among other things matter of counter critic on Riis' article, the nasty >= 0.0 match from Rybka's integer based - with Fruit's float based time control code was declared a litmus test of the whole topic. It was argued it could be a simple typo with only one additional trailing dot behind the zero. ‘0.’ already quantifies as float constant in C to force some compiler to emit the suspicious x87 instructions. Considering on how many places a chess program branches on the sign of an integer with >= 0 or < 0, it is peculiar that the typo happened exactly there, in that time control code where Fruit has ‘0.0’. However, Miguel A. Ballicora found the initial float condition was different in Rybka, not >= 0.0 but > 0.0, as published and mentioned by Ed Schröder in February 2012. The different > 0.0 condition was missed by the ICGA investigation panel, and implies the one and only possible literal copied line of Fruit code was at least modified.

Rebuttal
At January 08, 2012 the ICGA responds with two rebuttal articles on Riis' A Gross Miscarriage of Justice in Computer Chess, with an introduction letter from David Levy, President of the ICGA :

FIDE
In early 2012, the FIDE Ethics Commission received a complaint signed by Vasik Rajlich, co-signed by Søren Riis, Chris Whittington and Ed Schröder, against the ICGA. As announced at July 01, 2012, additional information is requested and the FIDE. Secretariat will communicate the decision to the complainants. The decision was made in April 2014. Parties are not allowed to publish the judgement as a whole, but may quote from it.

=See also=
 * Open letter to the ICGA about the Rybka-Fruit issue
 * Pre-Fruit Rybka and Crafty
 * Quantifying Evaluation Features

=Publications=
 * 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
 * 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
 * [[file:RybkaInvestigation.pdf]]


 * 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
 * David Levy (2012). No Miscarriage of Justice - Just Biased Reporting. doc
 * Mark Watkins (2012). A Critical Aanalysis of the four parts of Riis. pdf
 * Ed Schröder (2012). Rybka reloaded. pdf
 * Mark Watkins (2013). Review of the Rybka case. pdf
 * Jaap van den Herik, Aske Plaat, David Levy, Daniel Dimov (2014). Plagiarism in Game Programming Competitions. Entertainment Computing, Vol. 5, No. 3, pdf preprint
 * 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
 * Ed Schröder (2015). The myth Rajlich copied Fruit. pdf

=Forum Posts=

2011

 * Node counting by BB+, OpenChess Forum, January 20, 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, 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, 19 February, 2011 (Wayback Machine)
 * Programmers write open letter about Rybka-Fruit issue | ChessVibes by Peter Doggers, March 01, 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 by BB+, 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
 * 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 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
 * Vasik Rajlich responds to his accusers by Nelson Hernandez, Rybka Forum, July 12, 2011
 * In retrospect by Rebel, Rybka Forum, July 14, 2011
 * Fruit 1.0 PST by BB+, OpenChess Forum, August 13, 2011
 * Apology to Vas by Rebel, Rybka Forum, August 17, 2011
 * PST of Fruit 2.1 and Rybka 1.0 Beta by BB+, OpenChess Forum, August 22, 2011
 * Interesting reflection on a past statement by Graham Banks, CCC, October 22, 2011

2012

 * ChessBase: A Gross Miscarriage of Justice in Computer Chess by kingliveson, OpenChess Forum, January 02, 2012
 * Re: ChessBase: A Gross Miscarriage of Justice in Computer Chess by BB+, OpenChess Forum, January 02, 2012
 * Re: Hyatt Is Gone! by BB+ OpenChess Forum, Jan 03, 2012
 * Rybka evidence recapitulation by BB+, OpenChess Forum, January 03, 2012
 * ICGA response to ChessBase 4-part article by Robert Hyatt, CCC, January 08, 2012
 * A Big Thanks and a Small Update by Vasik Rajlich, Rybka Forum, January 08, 2012
 * Re: Another question for Vas by Vasik Rajlich, Rybka Forum, January 09, 2012
 * Fruit/Rybka timeline by BB+, OpenChess Forum, January 09, 2012
 * Rybka Investigation : Survey Of Evidence by Adam Hair, CCC, January 10, 2012
 * CB: Feedback on the ICGA/Rybka disqualification scandal by Ted Summers, CCC, January 13, 2012
 * Wiki-leaks by Ed Schröder, Rybka Forum, January, 18, 2012
 * "Fissure opens in chess AI scene" (Rob Beschizza/B by Julien Marcel, CCC, January 20, 2012
 * Rybka 1.0 source code by Ed Schröder, CCC, January 31, 2012
 * Andrew Dalke - copyright specialist by Rebel, Rybka Forum, February 02, 2012
 * On Dalke by BB+, OpenChess Forum, February 19, 2012
 * Rybka & ICGA at the FIDE Ethics Commission by vesuvio, Rybka Forum, August 17, 2012
 * In Retrospect: What have we learned from ICCA vs Rybka? by Bob Durrett, Rybka Forum, August 25, 2012

2013

 * Copying vs. stealing, ideas vs. source code etc. by Robert Hyatt, Rybka Forum, July 07, 2013
 * Bob: Harvey did most of the writing by Trotsky, Rybka Forum, July 22, 2013
 * Vas: could we have the final hearings in October or November, Rybka Forum, July 26, 2013


 * Bob used as a tool to do the dirty job by Jeroen, Rybka Forum, July 24, 2013
 * Open thread: a collection of Hyatt lies in the Rybka case by Jeroen, Rybka Forum, July 27, 2013
 * Was pre-beta Rybka ever "released"?, Rybka Forum, July 29, 2013
 * The jury, the judge and the prosecutor, Rybka Forum, August 01, 2013
 * Engine crash / incorrect mate score, Rybka Forum, August 08, 2013
 * adult discussions ;-), Rybka Forum, August 09, 2013


 * More Bob lies by Rebel, Rybka Forum, July 31, 2013
 * R.V. about Rybka 1.0 beta vs Fruit 2.1 by Richard Vida, Rybka Forum, August 11, 2013
 * Asides and commentary on RV's decompilation and reports by turbojuice1122, Rybka Forum, August 20, 2013


 * Bob's suggested punishment by Robert Hyatt, Rybka Forum, August 21, 2013
 * Complaining about formulas or ideas by Robert Hyatt, Rybka Forum, August 21, 2013
 * The originality claim... by user923005, Rybka Forum, August 23, 2013
 * Vas quotes and misquotes discussions by Robert Hyatt, Rybka Forum, August 26, 2013
 * The ICGA tribunal, what went wrong by user923005, Rybka Forum, August 28, 2013
 * Rule 2 interpretation by Trotsky, Rybka Forum, August 28, 2013
 * What does "copy" mean? by Trotsky, Rybka Forum, August 29, 2013
 * The obfuscation story by Rebel, Rybka Forum, August 29, 2013
 * Crafty/Fruit projection by Nick, Rybka Forum, August 30, 2013
 * Occam's razor vs Hyatt's razor by Rebel, Rybka Forum, September 01, 2013
 * Rook eval Rybka vs Fruit by Rebel, Rybka Forum, September 16, 2013
 * ChessVibes article by Nelson Hernandez, Rybka Forum, October 01, 2013

2015

 * Initiative in Stockfish vs. Crafty by Trotsky, Rybka Forum, April 07, 2015
 * Bob, 2015-04-20: FIDE has said this ...
 * Trotsky, 2015-04-20: Strange. Do we have the same copy of the FIDE EC decision?


 * FIDE Rules on ICGA - Rybka controversy by Jeremy Bernstein, OpenChess Forum, April 14, 2015
 * Complaint to FIFE Ethics Commission by Lukas Cimiotti, Rybka Forum, April 24, 2015
 * FIDE Ethics Commission ruling on ICGA/Rybka complaint by Graham Banks, CCC, April 24, 2015
 * FIDE Ethics Commission dealings (Case 2/12) by BB+, OpenChess Forum, April 24, 2015

2020 ...

 * Time to rethink what Vasik Rajlich has done? by Madeleine Birchfield, CCC, July 03, 2021

=External Links=
 * Attack of the clones | ChessVibes by David Levy, February 19, 2011 (Wayback Machine)
 * Schach-Software Rybka - Programmierer vermuten Intelligenzklau by Frank Patalong, Spiegel Online, March 03, 2011 (German)
 * Plagiatsvorwurf gegen Computerschach-Weltmeister, Heise online, March 01, 2011 (German)
 * Rybka disqualified and banned from World Computer Chess Championships | ChessVibes by Peter Doggers, June 29, 2011 (Wayback Machine)
 * 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
 * Computer chess reels from 'biggest sporting scandal since Ben Johnson' | Metro.co.uk by Tariq Tahir, June 30th, 2011
 * Schachcomputer-Weltmeister nachträglich disqualifiziert, Heise online, June 30, 2011 (German)
 * Weltmeisterprogramm Rybka verliert alle Titel by Frank Patalong, Spiegel Online, July 01, 2011 (German)
 * Developer of Computer Chess Champ Accused of Stealing Code by Dylan Loeb McClain, NYTimes.com, July 02, 2011
 * "Another Conversation with Vasik Rajlich" By Nelson Hernandez (on Rybka chess), July 04, 2011, YouTube Video


 * 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


 * Controversy over Rybka's disqualification and ban (UPDATE) | ChessVibes by Peter Doggers, January 08, 2012 (Wayback Machine)
 * The Rybka Investigation: A Survey Of Evidence From Both Perspectives by Adam Hair, January 2012, hosted by Ed Schröder
 * Feedback on the ICGA/Rybka disqualification scandal, ChessBase News, January 13, 2012
 * Fissure opens in chess AI scene - Boing Boing by Rob Beschizza, January 19, 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
 * Rybka case "greatest injustice perpetrated in computer chess history" (Part 1) | ChessVibes by Ed Schröder, October 01, 2013
 * Rybka case "greatest injustice perpetrated in computer chess history" (Part 2) | ChessVibes by Ed Schröder, October 05, 2013

=References= Up one level