Peterson–Stein formula

The Peterson–Stein formula is a result in the field of representation theory, particularly relating to the characters of semisimple Lie algebras. It provides a way to compute the values of certain characters of these algebras using simpler components. Specifically, the formula gives an expression for the characters of irreducible representations of a semisimple Lie algebra in terms of the characters of its subalgebras and the structure constants of the algebra.