Hi! First a quick note: all work on groups and integration with gap (especially libgap) will be very much appreciated!
On Mon, Mar 08, 2010 at 08:43:25PM -0800, Rob Beezer wrote: > An implementation of finite abelian groups would be at the top of my > list. Folklore has it many have tried - not sure just where it gets > hard. Then build the group of units mod n on top of that for its own > sake and as a demonstration of the more abstract class. I have some > code for the group of units in a worksheet someplace (which I can > share). Besides wishing for a more solid foundation to build on, I > ran out of steam as I tried to implement subgroups of same properly. > Maybe somebody can suggest somewhere else in Sage where an algebraic > substructure is done "right". Shameless plug: there is some work in progress in that direction, providing a standard architecture for implementing a quotient or subobject A of an existing parent B. I can't promise when it will be ready for integration into Sage, but we will be using it intensively soon. In short, the idea is that a new parent A just needs to provide a lift and retract map to/from B, and declare itself in the category Blahs().Quotients() (or Blahs().Subobjects()), and it will get for free default implementations for all the operations of the category Blahs(), by mean of lift and retract. http://combinat.sagemath.org/hgwebdir.cgi/code/file/tip/sage/categories/subquotients.py This sure does not solve all the issues, like how to best implement the lift and retract functions; which data structure to use for elements of the quotient, etc. But at least should get some trivialities out of the way. Also, for the record: I spent some time during Sage Days 20 discussing with Tobias Columbus, and he has taken on the project of implementing and/or improving the free objects for the classical categories like monoids, groups, abelian groups, algebras, ... There will be shortly a discussion on the topic on sage-combinat-devel. Cheers, Nicolas -- Nicolas M. Thiéry "Isil" <nthi...@users.sf.net> http://Nicolas.Thiery.name/ -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
