Abstract:
We consider special embeddings of a Lie subalgebra into simple Lie algebras. We classify the projections of algebra root systems and obtain the conditions under which a splint appears and the branching coefficients coincide with the weight multiplicities. Although such a coincidence is infrequent, it turns out to be connected with the Gelfand–Tsetlin basis.
Keywords:Lie algebra, special subalgebra, branching, weight multiplicity, splint.