Results 71 to 80 of about 1,449 (134)

Joint numerical ranges: recent advances and applications minicourse by V. Müller and Yu. Tomilov

Concrete Operators, 2020
We present a survey of some recent results concerning joint numerical ranges of n-tuples of Hilbert space operators, accompanied with several new observations and remarks.
Müller V., Tomilov Yu.
doaj   +1 more source

Second regularized trace of a differential operator with second order unbounded operator coefficient given in a finite interval

, 2017
In this work, we establish a formula for the second regularized trace of a second order differential operator with unbounded operator coefficient given in a finite interval. Mathematics subject classification (2010): 47A10, 34L20, 34B05, 34B09.
Özlem Baksi, Serpil Karayel, Yonca Sezer   +2 more
semanticscholar   +1 more source

Taylor spectrum and characteristic functions of commuting 2-contractions [PDF]

, 2007
In this work, we give a description of Taylor spectrum of commuting 2- contractions in terms of characteristic functions of such contractions.The case of a single obtained by B.Sz.Nagy and C.
Bendoukha, Berrabah
core   +1 more source

On the completely indeterminate case for block Jacobi matrices

Concrete Operators, 2017
We consider the infinite Jacobi block matrices in the completely indeterminate case, i. e. such that the deficiency indices of the corresponding Jacobi operators are maximal.
Osipov Andrey
doaj   +1 more source

Peripheral local spectrum preservers and maps increasing the local spectral radius

, 2016
We address two long standing problems in the context of local spectral radius preservers. First, we completely describe the form of maps preserving the peripheral local spectrum of product or triple product of operators.
A. Bourhim, Tarik Jari, J. Mashreghi
semanticscholar   +1 more source

Generalized Derivations and Norm Equality in Normed Ideals [PDF]

, 2011
2000 Mathematics Subject Classification: 47A10, 47A12, 47A30, 47B10, 47B20, 47B37, 47B47, 47D50.We compare the norm of a generalized derivation on a Hilbert space with the norm of its restrictions to Schatten norm ...
Barraa, Mohamed
core  

Maps preserving the local spectrum of some matrix products

, 2018
Let Mn(C) denote the algebra of all n×n complex matrices, and x0 a nonzero vector in Cn . For two fixed scalars μ and ν in C for which (μ ,ν) = (0,0) , we characterize all maps φ on Mn(C) satisfying σμST ∗S+νT ∗S(x0) = σμφ(S)φ(T )∗φ(S)+νφ(T )∗φ(S)(x0 ...
Z. Abdelali, Abdelali Achchi, Rabi Marzouki   +2 more
semanticscholar   +1 more source

On powers of operators with spectrum in cantor sets and spectral synthesis

, 2017
For $\xi \in \big( 0, \frac{1}{2} \big)$, let $E_{\xi}$ be the perfect symmetric set associated with $\xi$, that is $$E_{\xi} = \Big\{ \exp \Big( 2i \pi (1-\xi) \sum_{n = 1}^{+\infty} \epsilon_{n} \xi^{n-1} \Big) : \, \epsilon_{n} = 0 \textrm{ or } 1 ...
Zarrabi, Mohamed
core   +1 more source

Ultrametric Fredholm operators and approximate pseudospectrum [PDF]

Arab Journal of Mathematical Sciences
PurposeThe paper deals with ultrametric bounded Fredholm operators and approximate pseudospectra of closed and densely defined (resp. bounded) linear operators on ultrametric Banach spaces.Design/methodology/approachThe author used the notions of ...
Jawad Ettayb
doaj   +1 more source

Weyl's theorem and its perturbations for the functions of operators

, 2018
In this paper, we study the stability of Weyl’s theorem under compact perturbations, and characterize those operators satisfying that the stability of Weyl’s theorem does not hold for any integer powers of the operator. Mathematics subject classification
X. Cao, Jiong Dong, Jun Liu
semanticscholar   +1 more source