On the closed generalized Drazin-Riesz invertible operators and $C_{0}$-semigroups

TL;DR

This paper extends the concept of closed generalized Drazin-Riesz invertibility to unbounded operators and explores its relationship with $C_{0}$-semigroups, including applications to differential equations and examples of invertible generators.

Contribution

It generalizes bounded case results to closed operators and investigates conditions under which $C_{0}$-semigroup generators are closed generalized Drazin-Riesz invertible.

Findings

Established links between invertibility and $C_{0}$-semigroup theory

Characterized when generators are invertible in this sense

Provided examples including $C_{0}$-groups and differential equations

Abstract

This paper is a continuation of our paper [Med. J. Math 19, Article number: 31 (2022)] in which we extended the notion of generalized Drazin-Riesz invertible operators to closed operators. We establish here, results relating the notion of closed generalized Drazin-Riesz invertibility with the theory of $C_{0}$-semigroups. Firstly, we generalize results obtained in the bounded case [1] to the context of closed operators. Secondly, we investigate when an infinitesimal generator $A$ of a given $C_{0}$-semigroup is closed generalized Drazin-Riesz invertible. An application to $C_{0}$-groups and abstract second order differential equations is proposed, and an example of a $C_{0}$-group with closed generalized Drazin-Riesz invertible infinitesimal generator is given.