Computer Chess Club Archives




Subject: Re: What constitutes a clone?

Author: Lance Perkins

Date: 18:49:45 02/15/05

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Consider this scenario:

You saw someone else's code, then you went out and wrote your own code, which
ended up to be like the other code.

Even in this scenario, you could be violating the copyright of the other code.

The only way around this is with the 'clean room' approach. If you want to make
a similar or compatible code, you should have not seen the other person's code.
Instead, somebody else would see it, describe to you what it does, then you go
and write the code.

So, in all the cases where you stated that you took crafty's code and modifed
potions of it, it is considered a clone.

Let me go back to my novel example:

Assuming someone has written a 12-chapter novel. You then went and copied the
1st chapter, and then with your own ideas, you wrote chapters 2 to 12 which is
your very own original story. Can you submit this new novel to a publisher and
claim it as your own work?


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. 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 :-)

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