Functional identities involving inverses on Banach algebras

TL;DR

This paper characterizes classes of functional identities involving inverses and related mappings in unital Banach algebras, extending understanding of additive mappings satisfying specific algebraic identities with inverses.

Contribution

It provides new characterizations of additive mappings satisfying functional identities involving inverses and fixed elements in Banach algebras, with applications to Jordan and Lie products.

Findings

Characterization of additive mappings satisfying identities with inverses.

Results applicable to Jordan and Lie algebra structures.

Extensions of functional identity theory in Banach algebras.

Abstract

The purpose of this paper is to characterize several classes of functional identities involving inverses with related mappings from a unital Banach algebra $\mathcal{A}$ over the complex field into a unital $\mathcal{A}$-bimodule $\mathcal{M}$. Let $N$ be a fixed invertible element in $\mathcal{A}$, $M$ be a fixed element in $\mathcal{M}$, and $n$ be a positive integer. We investigate the forms of additive mappings $f$, $g$ from $\mathcal{A}$ into $\mathcal{M}$ satisfying one of the following identities: \begin{equation*} \begin{aligned} &f(A)A- Ag(A) = 0\\ &f(A)+ g(B)\star A= M\\ &f(A)+A^{n}g(A^{-1})=0\\ &f(A)+A^{n}g(B)=M \end{aligned} \qquad \begin{aligned} &\text{for each invertible element}~A\in\mathcal{A}; \\ &\text{whenever}~ A,B\in\mathcal{A}~\text{with}~AB=N;\\ &\text{for each invertible element}~A\in\mathcal{A}; \\ &\text{whenever}~ A,B\in\mathcal{A}~\text{with}~AB=N, \end{aligned} \end{equation*} where $\star$ is either the Jordan product $A\star B = AB+BA$ or the Lie product $A\star B = AB-BA$.