On Tue, May 5, 2009 at 10:41 PM, Robert Bradshaw
<rober...@math.washington.edu> wrote:
>
> On May 5, 2009, at 9:23 PM, Brian Granger wrote:
>
>> Michael,
>>
>> Thank you for bringing up this issue as it does clarify some aspect of
>> Sage derived code and licensing. But, in my mind, the "sage as
>> interpreter" aspect is a small perturbation on top of the zero-order:
>>
>> Sage = Python + GPL libraries
>>
>> That is, for the most part, I view the interpreter as Python itself.
>> But still the FAQ section is very clear that the presence of all the
>> GPL libraries loaded into an interpreter is sufficient to make sage
>> using scripts like Ondrej's GPL bound. I also understand that not
>> everyone agrees on this interpretation.
>
> The concept of "derivative work" transcends the GPL, what was quoted
> was the FSF's interpretation of copyright law, which is obviously
> going to be bias towards maximal viral impact. Personally, I think
> qualitative aspects are more important than technical aspects (static
> vs. dynamic linking) in asking whether or not something is morally or
> legally a derivative work.
>
> One could argue with exactly the same logic that a Mathematica
> worksheet is a derivative work of Mathematica, and a Matlab script is
> a derivative work of Matlab.
Note that the GPL is "viral", but the MATLAB/Mathematica/etc copyrights are not.
>> "When you share your Sage notebooks with me and other's in the class,
>> you must agree to license them under the GPL"
>
> I think sharing a worksheet, whether it be clicking on the "publish"
> button or emailing/posting a .sws file all have the same
> repercussions.
> In fact, flipping the permissions bit and pointing you
> to the file under a shared filesystem with the intent that you read
> it would probably classify as "distribution."
The GPLdistinguishes between sharing privately (in an organization)
and publishing publicly. See the GPL FAQ:
"Does the GPL require that source code of modified versions be posted
to the public?
The GPL does not require you to release your modified version, or
any part of it. You are free to make modifications and use them
privately, without ever releasing them. This applies to organizations
(including companies), too; an organization can make a modified
version and use it internally without ever releasing it outside the
organization.
But if you release the modified version to the public in some way,
the GPL requires you to make the modified source code available to the
program's users, under the GPL.
Thus, the GPL gives permission to release the modified program in
certain ways, and not in other ways; but the decision of whether to
release it is up to you."
--
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org
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