Rybka Disqualified and Banned from World Computer Chess Championships

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Rybka Disqualified and Banned from World Computer Chess Championships

David Levy - ICGA President

June 28th 2011

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:

Each program must be the original work of the entering developers. 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 their submission details. Programs which are discovered to be close derivatives of others (e.g., by playing nearly all moves the same), may be declared invalid by the Tournament Director after seeking expert advice. For this purpose a listing of all game-related code running on the system must be available on demand to the Tournament Director.

By claiming other programmers' work as his own, and failing to comply with the abovementioned 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 abovementioned 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:

Rybkahas 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:

[1] Vasik Rajlich is hereby disqualified from the World Computer Chess Championships (WCCC) of 2006, 2007, 2008, 2009 and 2010.

[2] 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.

[3] 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.


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


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


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


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

[4] 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.

[5] 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.

[6] 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)

[7] 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.

[8] 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

investigation files


19th World Computer Chess Championship
World Chess Software Championship
World Computer Chess Blitz Championship
16th Computer Olympiad
Advances in Computer Games 13 Conference

Tilburg, the Netherlands : November 18 to November 26, 2011

The ICGA is delighted to announce that our events for 2011 will be held in Tilburg, The Netherlands, hosted by the Tilburg University.

The dates are November 18 to November 26, 2011

This announcement serves also as a Call for Papers for the 13th ACG Conference. Full details of the conference can be found in the attach.

The university of grappa has graciously offered to host tournament results. The link: http://www.grappa.univ-lille3.fr/icga/event.php?id=43

Best regards,

Johanna Hellemons for the Board of the ICGA.


TCGA 2011/TAAI 2011

Dear all,

You are welcome to join the coming computer-game-related events held in Taiwan:
* TCGA 2011 tournament: to be held by Taiwan Computer Game Association (TCGA) on June 25-26, 2011. http://tcga.ndhu.edu.tw/tcga2011/.
* TAAI 2011 conference: to be held by TAAI on Nov. 11-13, 2011. http://taai2011.cse.yzu.edu.tw. Events in the conference include:
* CFP of IWCG 2011 (International Workshop on Computer Games): paper submission is due July 12, 2011. http://taai2011.cse.yzu.edu.tw/images/cfp-iwcg2011.pdf
(In principle, computer game related papers of TAAI 2011 will be moved to IWCG 2011)
* TAAI 2011 tournament. http://taai2011.cse.yzu.edu.tw/index.php/competitions

Thank you for your attention.

Best Regards,
I-Chen Wu


8th Annual Arimaa Man vs Machine Challenge Match

April 4th to April 24th 2011

Arimaa is a modern strategy game designed to be difficult for computers and yet playable with a standard chess set. The best players are currently humans. Each year a man vs machine match is held to determine if the best Arimaa playing program has surpassed the level of the top human players. A $10,000 USD prize is available until the year 2020 to develop such a program.

For more information about Arimaa see: http://en.wikipedia.org/wiki/Arimaa

For more information about the tournament visit: http://arimaa.com/arimaa/challenge/2011/


The ICGA Clone and Derivative Investigation Panel

Dear ICGA members,

The ICGA Clone and Derivative Investigation Panel has been founded. The Secretariat comprises Robert Hyatt, Mark Lefler and Harvey Williamson.

For the founding statutes see: www.icga.wikispaces.com.pdf


Attack of the Clones

by David Levy

As many of you will already know there has, in very recent years, been an upsurge of cases of cloning chess programs. The same has also happened in Go programming though to a much lesser extent.

I have just posted an article on this subject on the Chess Vibes web site:


I would urge all of you who are interested to read this topic.

As soon as we have a suitable forum set up the ICGA will be inviting interested parties from the chess programming community to take part in the debate and to assist the ICGA in helping to identify clones.


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