Diagonalization of Operator functions by algebraic methods

TL;DR

This paper establishes conditions for local diagonalization of analytic operator families between Banach spaces using algebraic methods, focusing on Jordan chain stabilization and power series solutions.

Contribution

It introduces algebraic criteria for diagonalizing operator families, including handling Jordan chains and constructing convergent power series solutions.

Findings

Finite pole order of the generalized inverse is achieved.

Smith form and smooth kernel/range continuation are established.

Conditions for local diagonalization are derived under Jordan chain stabilization.

Abstract

We give conditions for local diagonalization of an analytic operator family to a diagonal operator polynomial. The families are acting between real or complex Banach spaces. The basic assumption is given by stabilization of the Jordan chains at length k in the sense that no root elements with finite rank above k are allowed to exist. Jordan chains with infinite rank may appear. Decompositions of the linear spaces are constructed with corresponding subspaces assumed to be closed. These assumptions ensure finite pole order equal to k of the generalized inverse. The Smith form and smooth continuation of kernels and ranges to appropriate limit spaces arise immediately. An algebraically oriented and self-contained approach is used, based on a recursion that allows for construction of power series solutions. The power series solutions are convergent, as soon as analyticity and continuity of related projections are assumed.