Bases for the Representations of U4 in the Chain U4⊃U2+U2

Abstract
The highest‐weight polynomials of irreducible representations of U3 occurring in the reduction of the direct product of two irreducible representations are constructed from Young diagrams. The different irreducible representations in the product are labeled by a parameter which distinguishes their multiplicities also. The method of this paper can be easily extended to any Un.