CHANGE OF JORDAN STRUCTURE OF G-SELFADJOINT OPERATORS AND SELFADJOINT OPERATOR-VALUED FUNCTIONS UNDER SMALL PERTURBATIONS

Abstract

The author considers the problem of the change of length of Jordan chains when passing from -selfadjoint operator to -selfadjoint operator , provided is small enough. The role played by the so-called sign characteristics is clarified. The results will carry over to the case of small perturbations of holomorphic selfadjoint operator-valued functions.