> A "sparse" GCM (generalized Cartan matrix)
> can be implemented as list of items of the form
>
> (i,j,a_{ij},a_{ji})
>
> where i < j are elements in an index set.
> I guess this is a skew symmetric matrix with
> entries given by pairs (a_{ij},a_{ji}).What I now do is to allow any generalized Cartan matrix as input for Dynkin diagram, and then build from it the root system, root space, and weyl group. For finite Weyl groups, I would also give an optional argument to have it as a permutation group of the roots. But I also like the idea of having a very simple class containing only the generalized Cartan matrix. From this one could construct the root system (which should also behave as the set of all its roots, with iterators over all roots, positive roots, and negative roots), the root space, the Weyl group, and so on. -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To post to this group, send email to sage-combinat-devel@googlegroups.com. To unsubscribe from this group, send email to sage-combinat-devel+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sage-combinat-devel?hl=en.
