BB+ wrote:
there is the possibility that the Rybka code and the IPPOLIT code were written substantially by the same person/team, if I was investigating this, that's were I would put a strong line of questioning and research
I disagree with this. Why bother making so many changes if so, such as reordering the pieces, changing hash entries from 64-bit to 128-bit, etc. My take on the "goal" of IPPOLIT was to write something that was substantially un-Rybka-like if one investigated it with a fine-tooth comb, but to release it such a way that made it "obvious" that it was a clone. [Why, for instance, did IPPOLIT go unmentioned from May to October --- could the programmers not find a forum for it? Well,
maybe the authors gave up, as everyone thought they were kooks akin to "Ben Lau", but more likely they wished to play-up the "censorship" angle -- but I would rather stick with facts, as opposed to psychological speculation].
Firstly, congratulations on a fine report - the whole computer chess community should be grateful to you for it.
Reading the report quickly at first (I like to do this to get a 'feeling'), gave me two feelings
a) that from a top-down perspective both programs were quite similar
b) from a bottom up perspective both were quite different
and these feelings/conclusions remained on second, slower reading. In a sense top-down similarities are going to be about ideas, while bottom-up similarities would point to code copying. It's also going to be true that all chess programs are going to show top-down similarities by the very nature of the process and ideas known and so on, but this one gave me a feeling there was more, and I rationalised that to the idea that maybe there was a common developer involved somehow, or that both programs came from the same school. Just a feeling and maybe quite random.
If it were the same programmer, I don't find the 'differences' (you mention hash, piece order and so on) strange. At the end of a long iterative development process (several versions) one always has some unsatisfactory elements which are set in concrete somehow and difficult to change. The start again approach (which would probably be used by a departing programmer) is quite likely to lead to the sort of 'differences' you mention, simply because it is start-again and the unhappy set-in-concrete stuff cries out to be changed and can be easily changed.
I do agree with your pointing to the 'political aspects' of IPPOLIT. I see it myself for obvious reasons, but, for them, this was not just a program but a political statement delivered with an anarchic sense of humour and it was obvious to me at least right from the start that this was no stupid copy but an astonishing project by some very creative and funny guys having a lot of fun on the way. They set out to turn the world upside down and while some humourless ones may dislike their supposed anti-capitalist approach or their alleged intention to bring down the commercial side of computer chess, actually, bringing down the commercial side has been a strong thread in computer chess ever since I've been around, and is probably pretty much achieved by now.
So, for me anyway, the mixture of very high technical skill levels and knowledge, the mix with the slightly insane anarcho-politics and the lengthy determination to keep going in the face of censorship, abuse, bannings and lies all suggest a very bright and determined person(s) with a very strong personal investment brought about by some sort of personal contact that went sour. A man on a mission with all the strength brought about by being right while the mass of others was wrong. This guy, being right, was never going to be a copying cheat.
I would find it wholly plausible that IPPOLIT is a "reverse-engineered Rybka with many changes", and indeed I would assert that the IPPOLIT maker(s) certainly knew much of the internal workings of Rybka. It is not, however, merely a "code-based" copy therein (and my recollection is that the claim, at least at one point, was that code of Rybka appeared in IPPOLIT). I see no way to differentiate as to whether IPPOLIT "started from scratch" and implemented Rybka-like-parts one-by-one, or "started as a functional equivalent to Rybka" and then was modified (rather substantially). There are a few clues, for instance IPPOLIT computes Crafty-style bitboards at startup (as opposed to just having huge arrays in the executable), to indicate that at least some parts of IPPOLIT are completely independent (code-wise) from Rybka.
!