On May 6, 2009, at 12:29 AM, William Stein wrote: > On Tue, May 5, 2009 at 11:57 PM, Robert Bradshaw > <rober...@math.washington.edu> wrote: >> What about >> publishing (collections of) worksheets under the CC license? Code >> snippets in books? Are your books GPL compatible? (Maybe you could >> claim fair use.) >> >> I have no trouble licensing code under the GPL, but I do think this >> places an onerous and inappropriate burden on all *users* of Sage, >> and the GPL is supposed to be about modifying/distributing code. > > Building software on top of GPL'd libraries like Sage *does* have > serious implications toward sharing. That's sort of the point of the > GPL'd. There's no sense in hiding that.
For sure. That's perhaps the one useful purpose threads like this serve. > Suppose you spend three years implementing an algorithm as part of > Sage to compute X (say some Monsky-Washnitzer cohomology > computations). Then somebody else writes and publishes a clever paper > that includes a several-page Sage program that uses your > implementation of X (plus many other things in Sage) to compute Y (say > p-adic Regulators of Jacobians of genus 2 curves). Would you > definitely be allowed to use their new code and include it in Sage? I would be more apt to label this a derivative work (not just for convenience, the same would apply if I was the one building on someone else's stuff). If a paper had a chunk of code illustrating an elliptic curve has a needed property using the MW computations, I probably wouldn't. As an aside, I wonder how some journal would react to being legally required to provide the source in a machine readable format due to their being a distributor? (Guess one would have to work that out before publishing...) > I think the GPL was designed to ensure that computer programs that > build on your programs must be shared under compatible conditions. > This has the pro that it means that your work is protected in that > when people build on it, they can't "hoard" their improvements. It > has the drawback that it puts an onerous (and inappropriate?) burden > on those same people, that when they on your GPL'd work, they can't > hoard their improvements. > > In one sense at least, Sage can never be an alternative to > Maple/Mathematica/Matlab/Magma, etc. With the Ma's, if one wrote a > big program on top of them, and wanted to distribute the program as a > complete self-contained closed source program (say something like a > standalone Mathematica demonstration), at least it would be > technically and legally possible. One would have to do some sort of > contract with say Wolfram, Inc., but that's quite reasonable. With > Sage that would be impossible, since the copyright is spread over > hundreds of people (some dead). Scipy/Numpy/Enthought's stack > does provide this extra feature, which Sage never will. > > There's a little good and a little bad in everything. First off, I *definitly* think GPL is the right license for Sage, because of (and despite) all its implications. I guess my point is that I'm making a distinction between documents that happen to use Sage, and new programs built on top of Sage. In the former camp are things like tutorials and the homework exercise worksheets for your 480 class, or your modular forms and number theory books. These are not, in my mind, derivative works of Sage (though I'd hope people choose to keep them open). Of course there is a lot of grey area, and I think one hits the derivative work area long before one is shipping modified copies of Sage in its entirety. I would consider many Sage worksheets derivative works, but I don't think the implication is automatic. - Robert --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
