If G is a Lie group and H is a maximal subgroup, the branching rule G=>H is the rule describing how irreducible representations of G decompose into irreducibles of H. These are implemented in Sage as methods of the WeylCharacterRing, but until recently there were a few gaps in the built-in rules. Specifically, there were 20 cases of maximal subgroups of exceptional groups that had not been implemented yet.
The git branch public/combinat/15361-branching-rules, or the patch at: http://trac.sagemath.org/ticket/15361 now completes the branching rules from exceptional groups. I relied on results of Seitz and Testerman to complete these. Since branching rules from the classical groups were already in good shape, this means that all the branching rules listed in the tables of McKay and Patera (1981) are available in Sage. The patch also implements a BranchingRule class with a composition rule. This makes it easier to descend through the lattice of subgroups to a nonmaximal subgroup. I've posted a copy of the patched thematic tutorial here: http://sporadic.stanford.edu/thematic_tutorials/lie/branching_rules.html with fuller details. Dan -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-combinat-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-combinat-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-combinat-devel. For more options, visit https://groups.google.com/groups/opt_out.
