Allegations against another Chess Engine – The LOOP Program

By David Levy, London

The International Computer Games Association (ICGA) has received a formal complaint from Fabien Letouzey, the programmer of FRUIT, regarding the program LOOP. The allegation is that LOOP, which has participated in the World Computer Chess Championship, uses code derived from FRUIT, which placed second at the 2005 World Computer Chess Championship in Reykjavik.

LOOP was developed by Dr Fritz Reul. The ICGA has attempted to contact Dr Reul in order to give him the opportunity of commenting on the allegation prior to the ICGA conducting a technical investigation into LOOP, but it appears to us that Dr Reul does not wish to be found. The email address that had been used by Dr Reul is no longer active, so on behalf of the ICGA I sent him an email via someone who is known to be a friend of his and who indicated that he would pass my email on to Dr Reul. This intermediary did not wish to divulge Dr Reul’s current email address to the ICGA, which is of course perfectly acceptable behaviour.

Dr Reul did not respond to my email, hence this “open” announcement, which the ICGA is also asking Dr Reul’s friend to forward to him.

The purpose of this email and announcement is to advise Dr Reul that the ICGA is planning to conduct an investigation into LOOP in order to examine the allegation about the use of code derived from FRUIT, and to invite Dr Reul, once again, to contact the ICGA with his comments on the matter. If we do receive any communication from Dr Reul the ICGA will of course verify that the person communicating with us is indeed Dr Fritz Reul, the author of LOOP, before we enter into any discussion with him.

If Dr Reul does make contact with the ICGA he will be given every opportunity to defend himself against the allegations, including an invitation for him to comment on any evidence that the ICGA might consider during the investigation process.

If, by March 31st 2012, Dr Reul does not make contact with the ICGA in order to co-operate over this matter, the ICGA will commence its investigation “in absentia”.

Answer: Although Reul's thesis was supervised by Professor van den Herik the Loop program was not developed under the supervision of the ICGA. We have received a formal complaint from Fabien Letouzey about Loop and will be making a statement shortly to indicate how we are going to deal with it.

Søren Riis, London

My article “A gross miscarriage of justice in Computer Chess” [links below] was obviously a defense of Rajlich so in that sense David Levy is correct and my article can be said to show bias. However, while it’s acceptable that the defense and prosecution are biased, I find it wholly unacceptable if the people in charge of an investigation are. And please note by Levy’s own admission – the people in charge of the ICGA investigation already prejudged that Rajlich was guilty before the investigation started.

Levy begins the interview with an astonishing admission and shift in argument: Rajlich did not copy (or translate) code verbatim from Fruit, instead he undertook “non-literal copying”. But what exactly is non-literal copying? Maybe Levy's notion of non-literal copying is supposed to be about using underlying structures from Fruit? But the most important underlying structure, the data structure, couldn't be more different. Levy's notion of "non-literal copying" is so vague and subject to mischievous interpretation as to have no real meaning.

A reasonable use of the term "non-literal copying" would be an activity which is covered and forbidden by copyright law. In that case if Rajlich had engaged in "non-literal copying" he would be in breach of copyright law and Rybka would be a “derivative work” of Fruit. This is clearly not the case, as was argued in my article and also subsequently shown by an independent computer programming expert, Andrew Dalke, who looked at the case. Note also that the very fact that this input from Dalke exists at all bears witness to the fact that Levy is wrong when he says that the ICGA investigation had to be carried out by computer chess specialists and computer chess specialists alone. Per Levy's fallacious construct investigators need to be experts in “Pac-Man programming” in order to determine whether a “Pac-Man” program is original or breaching copyright laws.

Of course there is a good reason to have at least some "chess programmers" involved so they for example can assist with the "filtration" stages. As Andrew Dalke writes:

Chess programmers would be useful in pointing at which elements to use and which to filter in the ICGA (Watkins) comparison. However, it seems that the "chess programmers" were not involved in any filtering process, if such a thing even existed – they talk much about abstraction and comparison in their reports, but never filtration!

The correct way to state things is that Rybka implements ideas, concepts and algorithms that Rajlich learned from Fruit and other sources which gave Rajlich the tools to take chess programming to a new level of excellence. If Levy wants to call this "non-literal copying" it raises a host of thorny questions with answers that are inevitably highly subjective. What Rajlich took from Fruit complied with ICGA Rule 2 as stated, as well as satisfying copyright and license laws. Rybka was heavily inspired by Fruit but is not a derivative work of Fruit. In addition, Fruit itself took many ideas from other sources and also stands on the shoulders of previous giants of the genre. Robert Hyatt’s program Crafty is greatly indebted to Letouzey, Heinz, Slate/Atkin, Keenan, Slate/Sherzer and Shannon to name but a few. This is how computer chess programs are developed.

When the ICGA received the complaint letter from chess programmers, a wise response that would have shown responsible leadership could have been:

Such a response would have been fair and would have saved computer chess (as well as the ICGA) from a lot of trouble. There is however nothing wrong with the ICGA conducting an investigation. However, in addition to technical expertise, they should also have applied non-technical judgement and thought about a fair, proportionate and reasonable way to proceed. Bob Hyatt and other aggressive pre-judgers should have been kept away from the investigation. A massive failure of the ICGA investigation was the structure of the process; it is almost inconceivable that the decision was left purely to technical experts who unfortunately were blind to the veracity of the evidence presented as well as to the implications of what they were doing.

My ChessBase article sparked off debates also among software specialists outside the small "club" of chess programmers. For anyone who followed these debates it seems virtually certain that a thorough investigation conducted by neutral software specialists would have found the great chess programmer and world champion innocent and cleared his name.

Søren Riis is a Computer Scientist at Queen Mary University of London. He has a PhD in Maths from the University of Oxford. He used to play competitive chess (Elo 2300). In his latest email Søren wrote: "Just for your information: I withdrew as Rybka forum moderator almost immediately after the ChessBase article, as there were far to much mud slinging, and moderation became almost impossible and time consuming. So I have no formal links with Rybka which allows me to speak without any hidden strings attached.

Marcel van Kervinck, Netherlands

I would like to draw your attention to two points. First: in part one of his recent interview with ChessBase David Levy states the following: "Your question implies that Rajlich might only have copied a small and insignificant amount of Fruit, while the conclusion of the ICGA investigation was that a lot of code was copied." This does not represent my opinion as an active and voting panel member. Not now and not at the time of the investigation.

Code (=literal elements) was proven to be copied in a Rybka version that didn't compete in ICGA tournaments. But that didn't violate rule 2 because it didn't play in ICGA tournaments.

Formulas (=non-literal elements) was proven to be copied in Rybka 2.3.2a, which did compete in an ICGA tournament. Proven there was that more than just "ideas" were taken, but many Fruit-specific design choices that are rather arbitrary by themselves and unnecessary. But not proven was code copying in this version.

As such VR still violated the letter of the first sentence of rule 2. The rule's first sentence doesn't talk about "code", but about "program" and "work". An important distinction to make in representing what happened. (The logic of the later sentences of rule 2 makes it clear that "code" must not be taken as a synonym for "program" or "work", as is sometimes done in other contexts)

I therefore request you to rectify the above statement at ChessBase. You don't need it for your case and in your second part of the interview you are much more precise in your wording: there you say that Vasik Rajlich "used code derived from Fruit". I can accept that phrasing if it is intended to mean "Rajlich competed with code that he wrote, but which was derived from Fruit's design". And honestly, if that is what it means, that is how it should be phrased because it is too easy to misread otherwise. The most likely reason for the evaluation overlap in my opinion is that VR designed Rybka's evaluation first-most as an as faithful as possible replica of Fruit's without copying any lines of code in that process. From that point on, he worked to improve this evaluation.

But still many traces of Fruit's formulas are clearly visible in version Rybka 2.3.2a.

Second, I would also like to inform you that with the knowledge I have today, I would have voted differently in the investigation process. I will explain why: I'm not sure anymore that information provided for making a conclusion about the breaking of the 'spirit' of rule 2 was sufficient. In particular, the entry forms of prior entrants were not considered and should have been. I feel the investigators were insufficiently instructed about how prior entrants have declared their origins.
My specific interest is in the application form of the original entry of the Deep Thought team.

It was well-known at the time that DT was based on the design of Belle, and that Ken Thompson had given permission to the DT team to use that design as a template. It is not known wether this was written on the entry form. Why does this matter, you would say, because Fabien Letouzey should have given permission anyway. I will explain:

It was at the time well-known, by his own statements on his website, which was referenced on his entry form BTW, that Rajlich had studied Fruit extensively and had taken many things. And in my current opinion, Vas Rajlich did have Fabien Letouzey's permission to use Fruit's formulas in a WCCCh program.

The GPL license does allow that, unlike your statement in the ChessBase interview. The GPL can protect reproduction only. Entering a derived work in a tournament is not reproduction by the EU's copyright directive for software, which was applicable in Amsterdam. The fact that commercializing Rybka 2.3.2a might break the GPL is a civil matter between FL/FSF and Vasik Rajlich, and the ICGA should be no party in that.

I regret I didn't persist more at the time the comparison of Rybka's entry form with that of DT's. Because my vote should have been affected as follows:

• If DT's team did declare, on the entry form, that Belle's design was used, I would have voted Vas Rajlich guilty.
• If DT's didn't declare such on the form, I would have voted "not guilty, because there is no difference between DT's entry and VR's. Rule 2 should be applied the same."
• If DT's entry form was not to be found anymore, I would have voted "not guilty, because the information was insufficient to make an informed decision."

Previous articles on the ICGA/Rybka scandal

ICGA/Rybka controversy: An interview with David Levy (2) 10.02.2012 – On Monday we published part one of a lengthy interview we had conducted, via sequential email exchanges, with the President of the International Computer Games Association David Levy. The ICGA had found star programmer Vasik Rajlich guilty of "plagiarism" in his early program versions and banned him for life. Here now is part two of the interview.

ICGA/Rybka controversy: An interview with David Levy (1) 06.02.2012 – He is a star chess programmer with an unbroken record of supremacy in computer chess during the past five years. In June 2011 the International Computer Games Association found Vasik Rajlich guilty of "plagiarism" in early program versions and banned him for life. We published a vigorous defence of Rajlich and a rebuttal by ICGA President David Levy, who promised us an indepth interview.

Feedback on the ICGA/Rybka disqualification scandal 13.01.2012 – It's a long read, but many of the letters we received in reaction to the defence of the Rybka program by Dr Søren Riis are quite passionate and well thought out in their content. We start with the summary of a long rebuttal of the Riis paper that was sent to us by the ICGA and circulated on the Internet – with links to the full version and ancillary documents. Take a deep breath.

A Gross Miscarriage of Justice in Computer Chess (part four) 05.01.2012 – As proof that Vas Rajlich had copied program code the ICGA presented pages and pages of Fruit and Rybka code side by side. But, according to Dr Søren Riis, what was labeled as Rybka code was actually fabricated to look like Fruit. He criticizes the ICGA's process failures and ruminates on the reasons behind the unprecedented vendetta launched against the star chess programmer.

A Gross Miscarriage of Justice in Computer Chess (part three) 04.01.2012 – A core accusation against Vas Rajlich is that Rybka and Fruit have very similar positional evaluations, and the use of floating point numbers in Rybka’s time management code had to be copied from Fruit. Søren Riis enumerates the ten substantive evaluation differences and shows how the second accusation boils down to a single misplaced keystroke with zero impact on Rybka's play.

A Gross Miscarriage of Justice in Computer Chess (part two) 03.01.2012 – In this part Dr Søren Riis of Queen Mary University in London shows how most programs (legally) profited from Fruit, and subsequently much more so from the (illegally) reverse engineered Rybka. Yet it is Vasik Rajlich who was investigated, found guilty of plagiarism, banned for life, stripped of his titles, and vilified in the international press – for a five-year-old alleged tournament rule violation. Ironic.

A Gross Miscarriage of Justice in Computer Chess (part one) 02.01.2012 – "Biggest Sporting Scandal since Ben Johnson" and "Czech Mate, Mr. Cheat" – these were headlines in newspapers around the world six months ago. The International Computer Games Association had disqualified star programmer Vasik Rajlich for plagiarism, retroactively stripped him of all titles, and banned him for life. Søren Riis, a computer scientist from London, has investigated the scandal.

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