On another issue, one main reason why the Panel chose to start at R1 was that this was the Rybka version that
Fabien specifically claimed was Fruit-derivative (recall that
he was the genesis of the complaint to the ICGA), and also that various of the technical evidence had already been produced for this version. If Pradu Kannan had claimed that R4 was Buzz-derivative [he was contacted, and said the usage was OK by him], the investigation might have gone the other direction.
The Open Letter actually stated that R1 might be enough by itself(!):
It is very likely that later Rybka versions have derived and benefited from Rybka 1.0 beta and hence in the circumstances our view is they should also be considered derivatives of Fruit 2.1 until proven otherwise -- but the consensus in the Panel was that an approximate WCCC entry should be investigated, and preferably one that won the WCCC. The Panel then worked forward through Rybka versions [and backward, when the R161 evidence arrived], until the approximate 2007 WCCC winner was reached. All the R1-R232a versions were found to have (at the very least) the same problem of "evaluation overlap" with Fruit 2.1, with perhaps the later versions decreasing this very slightly. In particular, the Rybka 2.3.2a version from the 2007 WCCC specifically had its evaluation function completely analysed, and this was found to be "nonoriginal" with respect to the Fruit 2.1 evaluation -- it is simply incorrect to say that "almost everything (95%?) was based on R1beta" [and indeed, it would have saved me
many hours of evidence tracking/presentation if that had been the case].
As others have noted, there has been some "private" comparisons of R3 and later, but these were not considered in depth by the Panel for various reasons. Firstly, there is no longer as much reason to assume that R3/R4 have much resemblance to the 2008-10 WCCC entries as with R232(a)/2007. Secondly, there was nothing "obvious" to point to R3/R4 being a derivative (other than the Buzz/R4 issue), and enumerating evidence to prove a negative is often quite tedious. I was willing to make a statement that the
evaluation in R3 (at least), having been re-written by LK, was
likely now OK [though it seems that LK's name did not appear on the Rybka entry, or at least the ICGA never listed him as being a Rybka co-author -- but I digress], but to evidence this before the Panel would have required an enumeration of the R3 eval function, which seemed imprudent w/o VR giving an OK. It seems that minor UCI parsing peculiarities (
moves[-1] and "0.0", if indeed either is actually copied) still remain in R3. Some (not all) of the PST patterns remain the same, LK didn't modify
every evaluation consideration, etc. At the very least there would be something to discuss, as to whether there was still too much Fruit-influence.
Indeed to verify (say) R3 to the level of investigation as with the rest of the Panel deliberations would have involved showing/perusing large amounts of R3 disassembly, to ensure that everything was indeed "original". Furthermore, R3 is not freely available, and this could be a conflict for various Panel members (e.g., ZW does not own a copy, and is now a competitor to Rybka). And (as noted), there was almost a 2-month gap from R3 release to WCCC 2008, with various improvements made, such as bugs being fixed in private versions. For that matter, it's not completely insane [well, at least compared to some other theories] to suggest that R3 was "clean" due to [say] ChessBase concerns(!), but the "private" Rybka versions retained derivative parts (Fruit or otherwise).
The Panel chose instead to leave the question open, and let the Board decide what to do (e.g., request further investigation if they deemed that necessary for 2008-10). The Report lists various suggestions (ranging from Gerd Isenberg's to Mark Uniacke's) in this regard. When VR did not make a substantive response, the Board opted to close the case with their verdict. I will again link to the Wikipedia page on
evidential burden, and note that
Rajlich was disqualified and banned based on his behaviour, particularly with Fruit-nonoriginality for the [approximate] 2006-7 WCCC entries, and his ongoing refusal to address Rybka's origins (both with Crafty and Fruit) to the satisfaction of the Board with both these or later entries.
As #1 in the Verdict says:
Vasik Rajlich is hereby disqualified from the World Computer Chess Championships (WCCC) of 2006, 2007, 2008, 2009 and 2010, and only
then does it enumerate the consequences for
his entries therein. One might also note that the Panel
statutes say
nothing about the ICGA or even tournament participation(!):
The purpose of the Panel shall be to:
[a] Investigate and discuss allegations of cloning or creating a derivative of strategy games programs;
Report to the ICGA as to the veracity or otherwise of such allegations;
[c] Make recommendations to the ICGA as to what action if any should be taken against those found by the Panel to have been guilty of cloning or creating a derivative;
[d] Publish the findings of the Panel.
Indeed, whether an ICGA entry was necessary [either in general, or with respect to recommended actions] was an issue the Panel debated. The case of the KCC Paduk programmer being denied entry in 2009, due to events of a decade prior that were never addressed, is one example of precedent here.
I personally think the verdict was harsh, but inevitable in the circumstances. Given the mountainous evidence for R1-R232a, it seems unreasonable for the onus of evidence to remain with the ICGA, and contrarily seems quite reasonable for Rajlich to be requested to (say) show source code [e.g., privately to Ken Thompson, or some other distinguished person] for at least some later version, be it R3/R4/cluster or what. As this seems to be a non-starter from what Lukas Cimotti has said, the verdict was, as I say, inevitable.
), and/or when changes to EVAL were made.
-- indeed, internally in the Panel he was his usual "lightning rod" for contention, if for no other reason, because no one could bear to see him be correct. 