How is a POLL a way of determining this? Fools agree on many things. Various persons throughout history have even exploited this behaviour.
The question of whether Houdini 1.X is a "clone" of Y can be investigated with definite techniques, and rumours concerning the situation are unlikely to clear up the issue.
Programmers could easily distinguish the two and need not mixed them together.
Could and
do don't seem to be the same. Especially when there is reason to conflate the matter. For instance, I think the word
clone is still the word of choice for IPPOLIT and friends in some locales.
I would say that copying only ideas, no code, does not make for a derivative. Anyone care to weigh in?
I think this has been the historical standard in computer chess. As ZW and others have pointed out, the more recent events in the last years have made this less clear. The concept of Intellectual Property can also play a part.
Here is a scenario: Engine A has a material imbalance table of 419904 entries, computed from 8 parameters. Engine X has a similar table, also computed from 8 parameters (knight/pawn affinity, rook/pawn affinity, redundant major pieces...), which differ only slightly (all plus or minus 1 or 2 millipawns). Engine Y has a slightly simplified table, using only 6 of these 8 parameters, and rounds all the numbers to the nearest multiple of 5, after re-scaling from millipawns to centipawns. Engine Z has a material imbalance table with 419904 entries, using 5 parameters, 4 of which are used in Engine A, and has numbers that are kinda-sorta similar. Engine W has a material imbalance table with 236196 entries (not doing opposite-colour bishops)... It becomes not easy to make a cut-and-dried rule after a bit of this. I would say that W is clearly just the idea, probably Z is also, X is essentially a clone, and with Y more information would be needed. Now repeat this for other aspects of the code...