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   little we know -- Socrates

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Started in 1980, retired in 2004 REBEL was baptized into ProDeo, latin for gratis according to Dutch tradition.

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   Rybka-ICGA fiasco








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On June 28th 2011 IGCA president David Levy shattered the (computer) chess world with the announcement that programmer Vasik Rajlich, world champion computer chess in 2007, 2008, 2009 and 2010 with Rybka has been found guilty to have plagiarized the work of another chess program called: Fruit.

As a result Vasik Rajlich was banned for life, his 4 world champion titles were taken away, an ICGA press release followed that was picked up by the mainstream media containing all kind of juicy extensions and half truths. 

This page is meant to put things back into perspective and its main focus is to refute the technical evidence that was used againt Rajlich, see page Contra Investigation on programmer level in the left menu. Relevant less technical issues in the "External links" section.


Statements of dissenting (critical) chess programmers

  • Chris Whittington  games programmer and entrepreneur:
    There may be some anecdotal evidence for your model, but, as far as I can tell there is no good proof, just a groupthinky belief. Basically I think your argument is: Vas started with Fruit because he is a thief. Vas is a thief because he started with Fruit. Or, in other words, your argument is circular: the conclusion is the premise and the premise is the conclusion. More


  • Marcel van Kervinck  a Dutch software engineer and author of the chess program Rookie:

    Second, I would also like to inform you that with the knowledge I have today, I would have voted differently in the investigation process.  More

  • Ed Schröder  producer of the REBEL series and 2-times world champion:
    After 15 months of intensive research it's my final conclusion the accusers who investigated the Rybka chess program researched an original program. Strength is one aspect of originality and the way Rybka ruled (on equal hardware) was unprecedented in computer chess history. The ICGA verdict and ban are uncalled for and the event is a regretable moment in the history of computer chess. More


  • Sven Schüle  a German computer scientist and author of the chess program Surprise:
    This kind of statement has now been repeated by Bob approximately some thousands of times. So frequently that most people seem to have accepted this as a matter of fact, even many programmers who had doubts about it before. I also believe that Zach has done a great work by no doubt. I just do not share his final result, which is most important here. More


  • Miguel A. Ballicora  an Argentinean Biochemist and Associate Professor and author of Gaviota:

    Your question is a very good question. Taking ideas from one source? many? is it the same? I do not know, and probably there is no simple answer for ICGA purposes, but the question is relevant. The problem is, rule #2 is terribly worded and was designed eons ago with only cut&paste clones in mind. The part that says "e.g. programs that play nearly the same moves" (or something like that) is extremely naive. Let's suppose that I write a program following Ed's document about how rebels plays. That would probably be a program that is 80-90% identical. There was zero code copy because I did not even see it. Is that ok? I believe yes... what would be the difference if I saw the code? More


  • Dann Corbit  an American programmer and computer chess expert, tester and advisor:
    My main complaint is with the process of fault-finding itself. I think that the design of the process was flawed and with a flawed process flawed decisions are far more probable than via correct process. I do not expect the majority of chess programmers to agree with me or with my analysis. My opinion is mine alone but I wanted to say something since it appears to me that a bad process has been used to reach a final decision that affects a man's career in a significant way. More


  • Uri Blass  an Israeli mathematician and author of the chess program Movei:

    Rybka is not designed to be a copy of fruit and you cannot show me a big similiarity in the analysis between rybka and fruit that is a strange similiarity between different engines. More


  • Ronald de Man  a Dutch mathematician and computer scientist and author of the Sjaak chess engine:

    Certainly it does matter. We already KNOW that Vas is capable of adding 500 ELO to an engine when given enough time. That's how you brush away all arguments: not important, because he is guilty for all the OTHER reasons. In your world, all counterarguments fail BECAUSE HE IS GUILTY. More


  • José C. Martínez Galán  a Spanish computer chess programmer and author of Averno:

    People is not condemned for doing unsual things. To condemn someone, to be able to say you have proven guilt, you must refute even the most unusual possibilities. Otherwise, the "in dubio pro reo" must be applied. More

  • Charles Roberson  an American computer scientist and chess programmer author of the chess engines NoonianChess, Telepath and Ares and as ICGA panelist during the official voting: 
    I think the key to the Fruit eval issue is whether or not they both could have been inspired by other previous open source code and open technical discussions. On this issue, I've found some of Zach's paper to be incorrect as to the originality of Fruit's eval. 

  • Sergei Markoff  a Russian chess programmer and author of SmarThink:
    As the Rybka source was never published, the only possible thing to do with disassembly is to say that it contains a code that compiles at the same instuction sequences. But it's not a prove of direct copying of the code. More


    Now 2 years after the ICGA verdict

    where do we stand ?




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    Copyright ® 2011 Ed Schröder