COMPOSITION OPERATORS ON HARDY-ORLICZ SPACES

Properties of composition operators induced by analytic self-maps on the unit disk of the complex plane in Hardy-Orlicz spaces are discussed. Results are concerned about boundedness, invertibility, compactness, Fredholm operators and spectra of composition operators.     

On <Emphasis Type="Italic">K</Emphasis>-groups of operator algebra on the 1-shift space

In this paper we discuss the K-groups of Wiener algebra ;W. For the 1-shift space XGM2,We obtain a characterization of Fredholm operators on X^nGM2 for all n ∈ N. We also calculate the K-groups of operator algebra on the 1-shift space XGM2.     

ON THE GENERALIZED RESOLVENT OF LINEAR PENCILS IN BANACH SPACES

Utilizing the stability characterizations of generalized inverses of linear operator, we investigate the existence of generalized resolvent of linear pencils in Banach spaces. Some practical criterions for the existence of generalized resolvents of the linear pencil λ→ T λ S are provided and an explicit expression of the generalized resolvent is also given. As applications, the characterization for the Moore-Penrose inverse of the linear pencil to be its generalized resolvent and the existence of the generalized resolvents of linear pencils of finite rank operators, Fredholm operators and semi-Fredholm operators are also considered. The results obtained in this paper extend and improve many results in this area.     

Controllability of Nonlinear Discrete Systems with Degeneracy

This paper concerns the controllability of autonomous and nonautonomous nonlinear discrete systems, in which linear parts might admit certain degeneracy. By introducing Fredholm operators and coincidence degree theory, sufficient conditions for nonlinear discrete systems to be controllable are presented. In addition,applications are given to illustrate main results.     

Fredholm index and spectral flow in non-self-adjoint case

A version of the "Fredholm index = spectral flow" theorem is proved for general families of elliptic operators {A(t)} t∈R on closed (compact and without boundary) manifolds. Here we do not require that A(t), t∈R or its leading part is self-adjoint.     

A Note on Weighted Comp osition Op erators on the Fo ck Space

Based on a new characterization of bounded and compact weighted composition operators on the Fock space obtained by Le T(Le T. Normal and isometric weighted composition operators on the Fock space. Bull. London. Math. Soc., 2014,46: 847–856), this paper shows that a bounded weighted composition operator on the Fock space is a Fredholm operator if and only if it is an invertible operator, and if and only if it is a nonzero constant multiple of a unitary operator. The result is very different from the corresponding results on the Hardy space and the Bergman space.     

$(\omega)$性质及其摄动

In the note,we establish for a bounded linear operator defined on a Hilbert space the necessary and sufficient conditions for the stability of property(ω) by means of the variant of the essential approximate point spectrum and the induced spectrum of consistency in Fredholm and index.In addition,the stability of property(ω) for H(P) operators is considered.     

Property (ω) and Its Perturbations

In the note,we establish for a bounded linear operator defined on a Hilbert space the necessary and sufficient conditions for the stability of property(ω) by means of the variant of the essential approximate point spectrum and the induced spectrum of consistency in Fredholm and index.In addition,the stability of property(ω) for H(P) operators is considered.     

ON A CHARACTERIZATION OF THE S-ESSENTIAL SPECTRA OF THE SUM AND THE PRODUCT OF TWO OPERATORS AND APPLICATION TO A TRANSPORT OPERATOR

In this paper,we develop some operational calculus inspired from the Fredholm operator theory to investigate the S-essential spectra of the sum and the product of two operators acting on a Banach space.Furthermore,we apply the obtained results to determine the S-essential spectra of an integro-differential operator with abstract boundary conditions in L_1([-α,α]×[-1,1])(α 0).     

关于正则Fredholm多值线性算子对

将单值算子的Fredholm对的概念推广到多值线性算子的范畴上,讨论了Fredholm多值线性算子对的一些初等性质,在适当的条件下,获得了正则的Fredholm多值线性算子对的与正则Fredholm算子对的相平行的一些结果.     

Local Fredholm Spectra and Fredholm Properties of Singular Integral Operators on Carleson Curves Acting on Weighted Hölder Spaces

We study the local Fredholm spectra and global Fredholm properties for singular integral operators on composed Carleson curves with discontinuous coefficients acting on weighted H?lder spaces. We consider the curves, coefficients, and weights which are slowly oscillating at the nodes of the curve. Application of pseudodifferential operators technique allows us to explain the influence of oscillation of curves, coefficients, and weights on the appearance of massive local Fredholm spectra. We obtain a criterion of Fredholmness and index formula for operators under consideration.     

Fredholm theory forp-adic locally convex spaces

Summary The authors develop the Fredholm theory for semi-compact operators on non-archimedean locally convex spaces. This theory coincides with Schikhof's Fredholm theory for compact operators on Banach spaces which fails for non-complete normed spaces.     

Two-Dimensional Töplitz Operators with Measurable Symbols

For the complete algebra of two-dimensional Töplitz operators with measurable bounded symbols, we establish conditions necessary for the Fredholm property of the operators and prove results on the separation of singularities of the symbols. As a corollary, conditions sufficient for the Fredholm property are established for operators with symbols satisfying local conditions of sectorial type.     

An Invertibility Criterion in a C*-Algebra Acting on the Hardy Space with Applications to Composition Operators

In this paper, we prove an invertibility criterion for certain operators which is given as a linear algebraic combination of Toeplitz operators and Fourier multipliers acting on the Hardy space of the unit disc. Very similar to the case of Toeplitz operators, we prove that such operators are invertible if and only if they are Fredholm and their Fredholm index is zero. As an application, we prove that for “quasi-parabolic” composition operators the spectra and the essential spectra are equal.     

Spectral mapping theorem for generalized Kato spectrum

In this paper, we give an affirmative answer to Mbekhta's conjecture (Mbekhta, 1990 [13]) about the pseudo Fredholm operators in Hilbert space. As a consequence, we characterize pseudo Fredholm operators and we prove that the generalized Kato spectrum satisfies the spectral mapping theorem in the Hilbert spaces setting.     

Topological methods in solvability theory of multidimensional pair integral operators with homogeneous kernels of compact type

The problem of getting effective Fredholm conditions for operators with bihomogeneous kernels reduces to the question of invertibility for families of operators with homogeneous kernels and to the calculation of homotopy invariants for spaces of Fredholm and invertible operators of that type. The purpose of the present paper is to study integral operators with homogeneous kernels of compact type in L _p (? ⁿ ), 1 < p < +??. The classes of homotopy equivalence for the spaces of Fredholm and invertible operators in the C*-algebra of pair operators with homogeneous kernels of compact type are calculated by means of operator K-theory.     

Fredholm Indices of Band-Dominated Operators

The Fredholmness of a band-dominated operator on is closely related with the invertibility of its limit operators: the operator is Fredholm if and only if each of its limit operators is invertible and if the norms of their inverses are uniformly bounded. The goal of the present note is to show how the Fredholm index of a Fredholm band-dominated operator can be determined in terms of its limit operators.     

Left–Right Browder and Left–Right Fredholm Operators

We consider left and right Browder operators, left and right Fredholm operators, spectra related with these operators, and various operator quantities.