Proceedings of the American Mathematical Society, Vol. 91, No. 3 (Jul., 1984), pp. 426-432 (7 pages) This paper describes the spectrum and the upper and lower Fredholm spectra of (n + m)-tuples (F(A1) ...

Linear operators form the cornerstone of analysis in Banach spaces, offering a framework in which one can rigorously study continuity, spectral properties and stability. Banach space theory, with its ...

Abstract.In the present paper, we use the notion of measure of noncompactness to give some results on Fredholm operators and we establish a fine description of the essential approximate point spectrum ...