Published online by Cambridge University Press: 20 November 2018
Let G be a reductive group over a field of characteristic zero. Fix a Borel subgroup B of G which contains a maximal torus T. For each dominant weight X we have an irreducible representation V(X) of G with highest weight X. For two dominant representation X 1 and X 2 we have a decomposition
This decomposition is determined by the element
of the group ring of the group of characters of T.
The objective of this paper is to compute r(X 1, X 2) for all pairs X 1 and X 2 of fundamental weights. This will be used to compute the equations for cones over homogeneous spaces. This problem immediately reduces to the case when G has simple type; An, Bn, Cn, Dn , E 6, E 7, E 8, F 4 and G 2. We will give complete details for the classical types. For the case An we will work with GLn .