On Sep 24, 1:30 pm, "David Joyner" <[EMAIL PROTECTED]> wrote:
> On 9/24/07, Jaap Spies <[EMAIL PROTECTED]> wrote:
>
>
>
> > Jason Martin wrote:
> > > My vote would be to change the sage license to "GPLv2 or later" and
> > > try to get the Singular developers to do likewise. Mainly because
> > > that is less work.
>
> > > Does changing Sage to "v2 or later" require Sage to adopted future GPL
> > > changes? My interpretation is that it simply gives users the option
> > > to re-distribute it according to later versions of the GPL. It
> > > doesn't obligate Sage to adopt those future changes, does it?
>
If any file inside a project says GPL V2 only and the rest of the code
is licensed under a GPL V2 compatible license that in turn makes the
whole project if distributed in binary form GPL V2 only. That does not
apply to the sources! So if you see any file like that in Singular,
pari, GAP or whatever let the developer/copyright holder know and ask
them nicely to change the license to the same license as the rest of
the project.
We should also make sure that all our modifications to [L]GPL [2|3],
BSD, MIT licensed code are clearly licensed and we should make an
effort to merge our patches upstream.
> > If it says 'GPLv2 or any later version' version 2 still applies!
>
> "GPLv2 or later" means "you may copy, modify, and
> redistribute the code using either license GPLv2 or
> GPLv3 (at your preference)". You can't
> use both at the same time since they are incompatible.
Exactly, and this means: When releasing a Sage binary linked against
gmp 4.2.2 any source bits that are "GPL V2 or later" are in effect
covered under the GPL V3 only in that binary release, because any
[L]GPL V3 library forces the use of the compatible GPL V3 license. The
sources that are GPL V2 or later can still be used under GPL V2 and if
you choose to use gmp 4.2.1 and not any other [L]GPL V3 code the
resulting binary distribution is covered under GPL V2. Obviously the
other code that is BSD licensed retains its license.
As was pointed out in the thread before performance wise it won't make
any difference with Jason's patches. The are various bug fixes that
make it worthwhile to switch to the new release (even though there are
no new features beside the license change) and one patch went in to
support gcc 4.3, but that that one was mine (even though the patch
that went in did it differently). So I would suggest to license Sage's
code under GPL V2 or V3 (if you are paranoid about the successor of
GPL V3), but one should consider that once a hypothetical GPL V4 rolls
around some of the authors of Sage code might no longer be around/lost
contact to the project. So GPL V2 or later covers that and as long as
say William's contributions only are covered under "GPL V2 or V3"
nobody could realistically "hijack" Sage under a hypothetically bad
GPL V4, if you are that paranoid ;).
>
> > Even if GPLvx with x >= 3 is more restrictive.
>
> > Jaap
Cheers,
Michael
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