Hi Fabrizio,
Disclaimer: I am not a lawyer.
> SARAG of course is and should also be GPL or whatever license
> Maxima uses.
>
> SARAG is used by a freely downloadable book which does not
> contain SARAG but only uses it if it is in its directory.
>
> Springer owns the copyright of the book in both electronic
> and paper format.
>
> Springer might create a CD with the electronic book.
>
> Is Springer allowed to put unmodified versions of Maxima
> and/or SARAG in the CD containing the book even if
> they migh want to sell the CD with or without the paper book?
So far as I can tell from reading the GPL, yes,
they can put GPL software on a CD and sell the CD.
> I think I still have the right to give them the permission
> to put SARAG in the CD as long as this SARAG also remains GPL.
By releasing SARAG under GPL, you have already
given them permission to distribute SARAG under
the terms of GPL. You don't need to give permission again.
> I think I still own the copyright of any SARAG version
> I create myself and I could even give them more rights
> but I want to avoid that.
You should probably try to clarify with Springer whether
they expect that you signed over the copyright to SARAG
as well as the text of the book. If they think you did
and you think you did not, you might want to consult
a lawyer.
If Springer now holds the copyright to SARAG,
they can release it under any terms they want.
I don't think a copyright assignment can retroactively
affect already-released versions of SARAG, but it
certainly can affect future releases. So if it turns out
that Springer now holds the SARAG copyright,
please let us know; if that's the case, we'll have to
figure out what to do.
For what it's worth,
Robert