Generalized Powers of Substitution with Pre-Function Operators
Generalized Powers of Substitution with Pre-Function Operators
An operator on formal power series of the form S μS , where μ is an invertible power series, and σ is a series of the form t+（t2） is called a unipotent substitution with pre-function. Such operators, denoted by a pair (μ ，σ ） , form a group. The objective …