I will try to do some of that work (the part that i need for the braid groups), but i might need A LOT of help, since i have zero experience implementing classes in the category and coercion infrastructures.
Maybe the first aproach will be to make a (hopefully working) proof of concept, send it to the trak, and start improving from there. Any thoughts/volunteers? On 24 jun, 02:11, David Joyner <[email protected]> wrote: > On Thu, Jun 23, 2011 at 8:02 PM, kcrisman <[email protected]> wrote: > > > On Jun 23, 2:52 pm, David Joyner <[email protected]> wrote: > >> On Thu, Jun 23, 2011 at 2:40 PM, mmarco <[email protected]> wrote: > >> > I am trying to write an implementation of the Braid group in sage, and > >> > i am finding more dificulties than expected. The reason is that the > >> > categories that would be involved have very few implemented objects. > >> > For instance, the first very basic functionality i am implementing is > >> > just the naive free group arithmetic (with lists of integers). So i > >> > wonder if there is not implementation of the free group in sage > >> > already done (i have looked for it, to no avail). > > >> I think free groups are not yet implemented. It would be nice to have them. > >> They are of course in GAP (and GAP does have a braid > >> groups package). > > >http://www.sagemath.org/doc/reference/sage/categories/coxeter_groups.... > > > seems helpful. Maybe make an Artin group category? > > > David, do you think the GAP version would be too hard to wrap (and > > play nicely with our current groups)? > > Off the top of my head, I guess there would be a few ways one could wrap > GAP's braid package. One, is simply to wrap the commands, without > any understanding of the underlying mathematical > structure. The other would be to "properly" wrap the package by creating > the missing structures in Sage (eg, a FreeGroup class, etc), then > simply calling GAP/braid for the necessary computations. This latter > option would be very useful but a lot of work, IMHO. > > > > > We don't even seem to have free Abelian groups, really, though they > > are implicit several places, like in multiplicative Abelian groups and > > presumably the new additive class. > > >> > Another question i wonder is if the category framework would give > >> > support to group actions; and if it doesn't, which would be the > >> > apropriate aproach to implement them. > > > I think it should - for instance, there is currently work on group > > actions on integer vectors. > > > - kcrisman > > > -- > > To post to this group, send an email to [email protected] > > To unsubscribe from this group, send an email to > > [email protected] > > For more options, visit this group > > athttp://groups.google.com/group/sage-devel > > URL:http://www.sagemath.org -- To post to this group, send an email to [email protected] To unsubscribe from this group, send an email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
