On the Fredholm and Weyl Spectrum of Several Commuting Operators

Stability of essential spectra of bounded linear operators

In this paper‎, ‎we show the stability of Gustafson‎, ‎Weidmann‎, ‎Kato‎, ‎Wolf‎, ‎Schechter and Browder essential spectrum of bounded linear operators on Banach spaces which remain invariant under additive perturbations‎ ‎belonging to a broad classes of operators $U$ such $gamma(U^m)

Measure of non strict singularity of Schechter essential spectrum of two bounded operators and application

In this paper‎, ‎we discuss the essential spectrum of sum of two bounded operators‎ ‎using measure of non strict singularity‎. ‎Based on this new investigation‎, ‎a problem of one-speed neutron transport operator is presented‎.

THE DIRAC OPERATOR OF A COMMUTING d-TUPLE

Given a commuting d-tuple T̄ = (T1, . . . , Td) of otherwise arbitrary operators on a Hilbert space, there is an associated Dirac operator DT̄ . Significant attributes of the d-tuple are best expressed in terms of DT̄ , including the Taylor spectrum and the notion of Fredholmness. In fact, all properties of T̄ derive from its Dirac operator. We introduce a general notion of Dirac operator (in dimen...

φ-factorable operators and Weyl-Heisenberg frames on LCA groups

Weyl ’ S Theorem and Tensor Products : a Counterexample Derek Kitson ,

Approximately fifty percent of Weyl’s theorem fails to transfer from Hilbert space operators to their tensor product. As a biproduct we find that the product of circles in the complex plane is a limaçon. 0. Introduction To say that “Weyl’s theorem holds”, for a bounded operator T ∈ B(X) on a Banach space X , is to assert [2],[4],[5] that 0.1 σ(T ) \ ωess(T ) = π 00 (T ) ≡ iso σ(T )∩π 0 (T ) : t...