Which did you see as the conclusive evidence that code was copy-pasted? Section ...

waqf · on Jan 7, 2012

Ed Schröder, the initial accuser who recanted, states in summary:

"4. It is not possible to state categorically from the available data whether:

" 4a. Vas took Fruit source via cut and paste and converted to Rybka;

" 4b. Vas kept a copy of Fruit source open on another screen while he wrote Rybka himself;

" 4c. Vas absorbed ideas from Fruit (and other open sources) and then coded up Rybka hmself."

Source: http://www.top-5000.nl/evidence.htm — worth reading, but just as open to accusations of bias as the other links we've seen.

Someone · on Jan 7, 2012

Yes, section 4 says that, but I do not find that section convincing. IMO, some of its arguments are flawed. For example:

"integers are quicker than floating-point numbers"

Maybe in this case, but not in general, on all current hardware. Chances are that chess programs use little floating point code. If so, using a few floats here and there can even be faster because it allows the CPU to issue more instructions in parallel.

"According to Rajlich, he wrote a utility program (separate from Rybka and not available to users) in the C# language to generate his PSTs. As Fruit is written in C (not C#) this means there is a 100% certainty that Rajlich did not copy the Fruit PST generation code."

For low-level chess code (a bit of bit-twiddling, array lookups, arithmetic, but no library calls), I would think that porting C to C# can be an almost 100% copy-paste job.

Remarks like these make it hard for me to accept the conclusions as undeniably true. The "but everybody is doing it" argument, on the other hand, I found more convincing.