Stability of essential spectra of closed operators under T-compact equivalence and applications

Abstract

The main subject of this paper is to introduce and study the concept of T -compact equivalence of closed linear operators in Hilbert spaces. Many results are proved via this equivalence, especially the invariance of essential spectra of T -compact equivalent closed operators. The results obtained are used to describe some Fredholm essential spectra of transport operators. 2000 Mathematics Subject Classification: 47A53, 47A55, 47N50