Quasisymmetric function

Quasisymmetric functions are a class of special functions that generalize symmetric functions and are particularly important in combinatorics, representation theory, and algebraic geometry. They are defined on sequences of variables and possess a form of symmetry that is weaker than that of symmetric functions. ### Definition: A function \( f(x_1, x_2, \ldots, x_n) \) is called quasisymmetric if it is symmetric in a specific way.