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Subject: Re: Usage of egtb.cpp in GPL software (Amy, ExChess, ...)

Author: Gian-Carlo Pascutto

Date: 11:03:24 12/05/00

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On December 05, 2000 at 13:20:05, Dan Andersson wrote:

>I would say that its a problem for Amy and ExChess et al, not to Nalimov but >its easy to work around The authors ask Eugene for permission to use the code
>and point out what parts if any that are not GPL.

For Eugene, there is indeed no problem at all. For Amy and ExChess I
think things are not so easy.

The GPL says:

These requirements apply to the modified work as a whole.  If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works.

-> So far so good.

But when you distribute the same sections as part of a whole which is a work
based on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote it.

I think this basically means that if Amy and ExChess want to continue
using the Nalimov code they will have to get Eugene to grant a special
permission...that effectively puts that code under GPL, or stop
distributing their programs under GPL. Using GPL code and non-free code
together is a very complex issue. See the whole KDE/Qt drama. I am not
suprised running into this with the EGTB code, since it was a piece of
code with shaky copyrights that is used in GPL software.

I thought about making my own (GPL) tablebase generator, that would be
usable for chess variants like suicide also. However, making such a thing
efficient and generating all databases is another matter. Nalimov format
is very good.

>Easy Copyrigth link:
>
>http://www.templetons.com/brad/copymyths.html

It's a nice link but it doesn't help much trying to understand difficult
issues like using non-GPL code in a GPL program.

--
GCP



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