Robert Flesher wrote:Chris Whittington wrote:
The expert witness had already found the defendant guilty. All that remained was the writing of a suitable report. The language is biased, the reader is told what to think, where there are dissimilarities the reader is assured, for example, 'this is done for optimisation reasons only' and is left to assume the dissimilarity doesn't really exist. Where Rybka uses tables, the expert witness 'recreates' the code he imagines was used to build the table data (although he never saw the code in binary form!) and unsurprisingly it matches directly with Fruit code - well, if you want to find/prove something and are sufficiently biased and committed to the result ...... Please read that last bit carefully, again: the expert witness took a lookup table of data, imagined up the code required to recreate that data (this without access to the program that created the data which he has never seen), wrote the code as identical to some Fruit source, and says "it's the same, but optimised". Ridiculous, but it gets worse in this same code section ..... for the sub-function called in the above that looks at pawn defence in front of the king returns completely different values for each program, the sub-functions are given the same name by the witness, but they do different things. And, lastly on this section, what program doesn't look in some way at open files in front of the king? Just not good enough.
In king_safety as another example both Fruit and Rybka look at piece attacks on the eight squares around the king. Er, who doesn't do this? But it is treated as a similarity proof. The expert witness skips over the fact that Rybka does it all very fast with btiboards (who wouldn't with a bb program?), while Fruit code is longer and slower, done without bb's (well it would be wouldn't it?). We're told that the 'sum of weights' for the attacks are different for each program, but the fact that pawns are treated as zero (what a surprise!!) is yet more 'proof' of similarity, while all differences (massive I would imagine) are just the result of 'optimisation' (again). Hahahaha!!!
Just for starters.
In a court the witness document would be torn apart and rapidly discredited. I am shocked that elements of comp chess community have placed so much weight on it.
Thanks for your input Chris. Many of us here are not programmers so we cannot make the assessment that you and other experts can. So then we are forced to make a conclusion based on what other experts say about the evidence or document. Zach's report was not really questioned until now (from what I have seen), so there was no reason to doubt its claims. However, other than stating you feel it is slanted and biased could you further clarify for the rest of us. Is it accurate? Could you dumb it down for the rest of us non technical idiots?
Thanks
There's two 'reports' written. One, anonymous or semi-anomymous, by BB and another by the known programmer Zach Wegner. BB's report is written in a relatively neutral style, the reader is left to form his own conclusions, it comes across as a good neutral expert witness style report, difficult to criticise for bias or pre-formed conclusions.
Zach's report is written very much in adversarial style. It's less of an neutral expert witness report and more of a prosecuting lawyer's report, with desire to paint the defendant(?) in as negative a way as possible. Fair enough, Zach is not neutral, he has plenty invested in a guilty verdict. An adversarial report can't be taken as truth, truth in an adversarial system is reached by adversarial defence, in other words, Zach's report NEEDS to be attacked, adversarially - truth comes from that process.
I'm surprised it took months for the obvious hole to be seen. I guess most people just skim read because it's too difficult or skim read because they don't want to find any holes.
However, if Zach is presenting his report with material that prima facie appears damning, but actually isn't, then he is guilty of being misleading and the entire report is compromised.
Bob's duck quacks like a chicken.