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Subject: Re: What constitutes a clone?

Author: Andrew Williams

Date: 02:36:28 02/16/05

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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?
>
CLONE

>How about if the author rewrote the evaluation code and search algorithm only,
>but left the hashing code, et. al.?
>
CLONE

>How about if the author rewrote everything EXCEPT for the evaluation?
>
It's hard to tell how this could be done, because the evaluation will be deeply
integrated into the rest of the program. CLONE, but why bother?

>How about if the author rewrote everything EXCEPT for Crafty's evaluation of
>passed pawns?
>
See previous comment. CLONE, but why bother?

I think evaluation and search are bad examples, because I feel that they define
an engine in a way that many of the other parts don't. For example, if someone
adopted Crafty's book format and access code - assuming they followed the terms
of crafty's license (I don't know what those terms are), I wouldn't call that
program a clone.

>I think you can see where I'm driving. Obviously, many engine authors have
>studied Crafty and other engines whose authors have graciously provided their
>source code. But, for an engine to not be considered a clone, does it have to be
>absolutely 100% the work of the author? (Forget about Nalimov's EGTB probing
>code and any other code that can be used with permission).
>
>Many thanks in advance for your thoughts,
>
>jm (who's just preparing for any eventuality during his upcoming stint as
>moderator :-)

Interesting questions!

Andrew



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