On the perturbations of spectra of upper triangular operator matrices

In this paper we investigate perturbations of the left essential spectrum, right essential spectrum, essential spectrum and the regular spectrum of an upper triangular operator matrix such as M sub C - [A sub 1 sub 1 C sub 1 sub 2 O sub 2 sub 1 B sub 2 sub 2] acting on a Hilbert space H + K

On the perturbations of spectra of upper triangular operator matrices

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal