Inverses et propriétés spectrales des matrices de Toeplitz à symbole singulier
Inversion d’un opérateur de Toeplitz tronqué à symbole matriciel et théorèmes-limite de Szegö
Ce travail est une étude théorique d’opérateurs de Toeplitz dont le symbole est une fonction matricielle régulière définie positive partout sur le tore à une dimension. Nous proposons d’abord une formule d’inversion exacte pour un opérateur de Toeplitz à symbole matriciel, démontrée au moyen d’un théorème établi en annexe et donnant la solution du problème de la prédiction relatif à un passé fini pour un processus stationnaire du second ordre. Nous établissons ensuite, à partir de cet inverse, un...
Inversion of matrix convolution type operators with symmetry.
Inversion von Fredholmfunktionen bei stetiger und holomorpher Abhängigkeit von Parametern.
Inverspositive Operatoren und Taubersätze in der Erneuerungstheorie.
Invertibility characterization of Wiener-Hopf plus Hankel operators via odd asymmetric factorizations.
Invertibility of matrix Wiener--Hopf plus Hankel operators with APW Fourier symbols.
Invertibility of the commutator of an element in a C*-algebra and its Moore-Penrose inverse
We study the subset in a unital C*-algebra composed of elements a such that is invertible, where denotes the Moore-Penrose inverse of a. A distinguished subset of this set is also investigated. Furthermore we study sequences of elements belonging to the aforementioned subsets.
Invertibility preserving linear mappings into M₂(ℂ)
We study discontinuous invertibility preserving linear mappings from a Banach algebra into the algebra of n × n matrices and give an explicit representation of such a mapping when n = 2.
Invertibility-preserving maps of -algebras with real rank zero.
Invertible and normal composition operators on the Hilbert Hardy space of a half–plane
Operators on function spaces of form Cɸf = f ∘ ɸ, where ɸ is a fixed map are called composition operators with symbol ɸ. We study such operators acting on the Hilbert Hardy space over the right half-plane and characterize the situations when they are invertible, Fredholm, unitary, and Hermitian. We determine the normal composition operators with inner, respectively with Möbius symbol. In select cases, we calculate their spectra, essential spectra, and numerical ranges.
Invertible composition operators on Banach function spaces
Irreducible Compact Operators.
Is an operator on weak which commutes with translations a convolution ?
Isolated points of spectrum of k-quasi-*-class A operators
Let T be a bounded linear operator on a complex Hilbert space H. In this paper we introduce a new class, denoted *, of operators satisfying where k is a natural number, and we prove basic structural properties of these operators. Using these results, we also show that if E is the Riesz idempotent for a non-zero isolated point μ of the spectrum of T ∈ *, then E is self-adjoint and EH = ker(T-μ) = ker(T-μ)*. Some spectral properties are also presented.
Isometric composition operators on weighted Dirichlet space
We investigate isometric composition operators on the weighted Dirichlet space with standard weights , . The main technique used comes from Martín and Vukotić who completely characterized the isometric composition operators on the classical Dirichlet space . We solve some of these but not in general. We also investigate the situation when is equipped with another equivalent norm.
Isometries between groups of invertible elements in Banach algebras
We show that if T is an isometry (as metric spaces) from an open subgroup of the group of invertible elements in a unital semisimple commutative Banach algebra A onto a open subgroup of the group of invertible elements in a unital Banach algebra B, then is an isometrical group isomorphism. In particular, extends to an isometrical real algebra isomorphism from A onto B.
Isometries in , generating functions and extremal problems
Isometries of Musielak-Orlicz spaces II
A characterization of isometries of complex Musielak-Orlicz spaces is given. If is not a Hilbert space and is a surjective isometry, then there exist a regular set isomorphism τ from (T,Σ,μ) onto itself and a measurable function w such that U(f) = w ·(f ∘ τ) for all . Isometries of real Nakano spaces, a particular case of Musielak-Orlicz spaces, are also studied.
Isometries of Orlicz Spaces of Vector Valued Functions.