Thanks -- All this week (off and on) is ok, and I expect that my afternoons will be your mornings, my evenings your afternoons. For the 3 weeks after this I'll be much harder to get hold of.
John On 9/24/07, David Roe <[EMAIL PROTECTED]> wrote: > John, > At the end of the spring I began working on porting your Magma code > implementing Tate's algorithm for elliptic curves and p-adic heights to > Sage. I made a lot of progress, but discovered that I needed to write a few > new classes for elliptic curves over number fields. It sounds like some of > the infrastructure that you're trying to implement is exactly what I was > working on before I got too busy this summer to work on Sage. > > I have some time to work on Sage this week. Let me know when you're free > and perhaps you, David and I can work on it together, though this might be > interesting given our different time zones (I'm in Boston). > another David > > > On 9/24/07, John Cremona <[EMAIL PROTECTED]> wrote: > > > > > > David, > > > > I'm sure you are right but doing that on my own (and in the next day > > or two) is beyond my sage/python capabilities... to start with (and > > as these isomorphisms of Weierstrass models are so much simpler than > > more general isogenies) I was going to be much more simple-minded and > > just have a list [u,r,s,t] of elements on the field of definition of > > the curve, with no fancy parent structure. > > > > On the other hand, if you'll have some time this week then perhaps we > > could do it as a joint effort from which I would learn a lot! > > > > John > > > > On 9/24/07, David Kohel <[EMAIL PROTECTED]> wrote: > > > > > > Hi John, > > > > > > I would strongly suggest that this construction be compatible > > > with isogenies (also yet to be implemented). Thus one should > > > be able to compose isomorphisms and isogenies with one > > > another. Moreover, one should be able to access the defining > > > polynomials -- this is useful to verify the definitions of > > > coefficients > > > of the transformations u,r,s, and t. > > > > > > The intend is that isomorphisms would have a parent structure > > > Iso(E,F) [or Isom(E,F)] and Aut(E) = Iso(E,F) which really only > > > need to coerce into the more general Hom(E,F) and End(E). > > > > > > Certainly the transformations would be useful for construction > > > of minimal models. > > > > > > If a proper class of isogenies is defined, then adding the parent > > > and coercions can be added easily. > > > > > > --David > > > > > > > > > > > > > > > > > > > -- > > John Cremona > > > > > > > > > -- John Cremona --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
