thanks for your advice. I'll try to write a new class, but i won't try to merge it into SAGE ! i'll just try to use reasonable names for the methods, so that my examples remain compatible with whatever improvement gets written for SAGE one day... for the "database" i'll use a dict indexed by the "group ID" as GAP understands it.
will keep you posted, but don't hold your breath, i'm afraid i have a lot to do these days ! pierre On Jan 19, 4:57 pm, John H Palmieri <jhpalmier...@gmail.com> wrote: > On Jan 19, 6:28 am, Pierre <pierre.guil...@gmail.com> wrote: > > > hi all > > > I've just realized that SAGE knows about the Steenrod algebra now. > > Does it know about unstable modules, too ? > > No, it doesn't, unfortunately. (Sage doesn't know about tensor > products, which has delayed me from implementing various things, like > the coproduct, and I suppose modules.) > > > I have another, related question. I have computed the unstable module > > structure on the mod 2 cohomology rings of quite a bunch of finite > > groups, see > > >http://www-irma.u-strasbg.fr/~guillot/research/cohomology_of_groups/i... > > This looks very nice. > > > I was thinking that I should, somehow, provide a file readable by SAGE > > so that people could use these algebras. > > Sure. > > > For one thing it would > > provide many examples of unstable modules, which is always good to > > test ideas about the Steenrod algebra. And regardless of the steenrod > > operations, even the cohomology rings, as computed by Carlson and > > others, are not available in SAGE yet (they're there as Magma files). > > At this point I can relatively easily provide a partial translation > > into SAGE. > > I think Simon King does some group cohomology computations with Sage, > but I don't know exactly how he does it. > > > However I was wondering about the best "format" for this: assuming the > > unstable algebra class does not exist, shall I present the algebras as > > quotients of polynomial rings ? or just give a couple of SAGE lists > > with the generators and relations, possibly just members of the formal > > ring ? or something pickled perhaps ? I really don't know. Note that > > I've got more information on these algebras yet (Stiefel-Whitney > > classes...) > > It sounds to me as though you should create a new class, the > UnstableAlgebra class, or the ModularGroupCohomology class, or > something, which should derive from the class of quotients of > polynomial algebras (so you can define at least part of the structure > by specifying such a quotient), and then there should be extra > structure: the Steenrod operations and Stiefel-Whitney classes and > whatever else you have. > > > And shall I think of a mechanism for people to download ALL the > > examples at once rather than separately ? (perhaps useful to try a > > conjecture about unstable modules ?) > > You might have two files: one which defines the class, and another > which presents all of the examples. I haven't used databases in Sage, > but perhaps the examples could be a dictionary indexed by the group, > or something like that? > > I'm looking forward to whatever you come up with. > > John Palmieri > > > suggestions most welcome. > > Thanks, > > > pierre --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
