Author: Mridul Muralidharan
Date: 22:39:47 02/15/05
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On February 15, 2005 at 21:08:08, Andrew Wagner wrote: >On February 15, 2005 at 18:38:43, John Merlino wrote: > >>I'm not trying to start a brutally long thread here, but I'm just curious about >>how people feel about a particularly touchy subject -- clones. What, in your >>mind, would lead you to the conclusion that an engine is a clone? >> >>Let's forget trying to find ways to PROVE that a clone is a clone; I'm just >>trying to define one. For the sake of argument, assume that the author of this >>engine in question tells you exactly what he did and did not do, and you must >>decide whether to call it a clone or not. >> >>Here are some hypothetical questions to start the debate: >> >>If the author took Crafty and completely rewrote the evaluation code and nothing >>else, would it be a clone? >> >>How about if the author rewrote the evaluation code and search algorithm only, >>but left the hashing code, et. al.? >> >>How about if the author rewrote everything EXCEPT for the evaluation? >> >>How about if the author rewrote everything EXCEPT for Crafty's evaluation of >>passed pawns? >> >>I think you can see where I'm driving. > >[snip] > >To add a completely useless illustration, this reminds me of an age-old riddle. >A bald man is someone who has no hair. What about the person with one hair? >Well, ok, for all intents and purposes, he's bald too. What about the guy with >two hairs? You gotta admit, we would consider him bald, too. And you can keep >going on like this. Where's the line? > >As was pointed out elsewhere in this thread, you can't "steal" a line like 'int >i;'. That's just standard coding practice. But I think if there's some concept >that an engine uses uniquely, that you use without giving credit, that's a >violation of the GNU licensing agreement. I don't know that you can call the >whole engine a clone, but that part of it is certainly inappropriate. Good point - and I like the analogy :) In computer chess especially , there are hardly any "secrets" - yes there are tuning params , variations of move ordering , pruning , etc - but all techniques are "known" (well , commercials might have something "interesting" ;) ) Eval is also an approximation and gross simplification of what humans consider. So when will you start accusing someone of cloning ? I think only the laziest of programmers who are cloners will get caught - sadly :( with some imagination , I am pretty sure that even with most of the code intact , you can make an undetectable clone of fruit or gnuchess or crafty. Mridul
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