The Evidence against Rybka

[hyatt]

I think there are two issues here. The op[side] vs non-duplicated code. I have no duplicated code in Crafty. But I also don't use an opening[color] and endgame[color] array either. I believe your comment was right about it being useful for unrolling the loop. The issue would be that if the white and then black loop iterations are unrolled, OOE can do both in parallel since they update different scores. I have thought about modifying my code to do this, as the current program loops over the scoring function calls twice, once for black, and once for white, and they can't be "unrolled" because of a data dependency on the score variables (2) that get updated.

Not that this matters, of course. It's just another weak attempt to find anything at all that might somehow be exculpatory. This definitely is not "that anything at all" however...

[Rebel]

My understanding was this was on purpose. Fabien wrote the code so it would work from either side, so he just looped over the to sides and correct for black by subtracting. A classic speedup trick is to unroll the loop, and this is what was done in Rybka. Save a little time since the two score do not need to be combined.

Assumption on assumption on assumption is good science ?

No, not an assumption. My understanding. Fabien discussed his programming philosophy either on one of these forums or in a private email. I will try to find a quote. But the basic idea was to keep things simple. By coding things once but having the code aware for each side, you avoid silly errors like forgetting to add a new term in two different places for each side. Granted, it might be a bit slower, but it is easier to understand and less prone to programming errors since the code is about half the size. Fabien preferred clarity over speed. I recall in some Fruit release notes he said "bear in mind mobility is a costly feature, when implemented in a straightforward way as I did" making it clear he likes clear, straight forward code over clever, faster and more confusing code.

Different is different.

[veritas]

pig headed is pig headed

[Jeremy Bernstein]

pig headed is pig headed

Consider this your final warning, veritas/venus/angel. Your posts are neither insightful nor helpful; they are simply personal, rude provocations and this forum can do without them. Final warning means account, email and IP range blocked immediately and indefinitely if it continues.

Thanks for your understanding,
The Mgmt

[veritas]

your sweeping generalization is subjective opinion and IMHO biased , what posts you may see as useless uninformative etc may well be seen differently by others, ie the download and information to help fix the stockfish problem
and in the U.K and in parts of Germany i have lived "pig headed " is a term for "stubborn " NOT an insult
but do please yourself as to how YOU choose to interpret anything i might write , it is your prerogative even if biased , prdjudiced and unjust

[hyatt]

Different is different.

I think everyone pretty much gets your perspective. If Vas changed just one character out of the maybe 1,800,000 characters (size based on a wc of crafty's source) then Rybka is "different." Not EVERYONE agrees with that perspective, however. In fact, just a tiny group at Rybka Forum will buy that argument. Not the ICGA. Not the courts if FSF follows through.

Our perspective has been to look for all the similarities. Yours is to just find ONE difference. That's a huge gap between the two. As in the difference between syntax and semantics.