Results 31 to 40 of about 137 (130)

Cohyponormality of Unbounded Product of Composition Operators in L2 Spaces

Journal of Function Spaces, Volume 2025, Issue 1, 2025.
Let X,A,μ be a σ‐finite measure space. The composition operators Cϕ:DCϕ⟶L2μ are defined by Cϕf=f∘ϕ,f∈DCϕ, where ϕ are nonsingular transformations and DCϕ=f∈L2μ: f∘ϕ∈L2μ. Suppose that ϕ1, ϕ2, ⋯, ϕn are nonsingular transformations of X, where n ∈ ℕ and n ≥ 2.
Hang Zhou, Qing Su, Nikhil Khanna
wiley   +1 more source

Hyponormal Toeplitz Operators on the Dirichlet Spaces

Abstract and Applied Analysis, Volume 2013, Issue 1, 2013., 2013
We completely characterize the hyponormality of bounded Toeplitz operators with Sobolev symbols on the Dirichlet space and the harmonic Dirichlet space.
Puyu Cui, Yufeng Lu, Natig M. Atakishiyev   +2 more
wiley   +1 more source

Fractional powers of hyponormal operators of Putnam type

International Journal of Mathematics and Mathematical Sciences, 2005
We are concerned with fractional powers of the so-called hyponormal operators of Putnam type. Under some suitable assumptions it is shown that if A, B are closed hyponormal linear operators of Putnam type acting on a complex Hilbert space ℍ, then D((A+B¯)
Toka Diagana
doaj   +1 more source

Optimisation of laser welding of deep drawing steel for automotive applications by Machine Learning: A comparison of different techniques

Quality and Reliability Engineering International, Volume 40, Issue 1, Page 202-219, February 2024.
Abstract Laser welding is particularly relevant in the industry thanks to its simplicity, flexibility and final quality. The industry 4.0 and sustainable manufacturing framework gives massive attention to in situ and non‐destructive inspection methods to predict laser weld final quality.
Giacomo Maculotti, Gianfranco Genta, Maurizio Galetto   +2 more
wiley   +1 more source

A New Seminorm for d-Tuples of A-Bounded Operators and Their Applications

Mathematics, 2023
The aim of this paper was to introduce and investigate a new seminorm of operator tuples on a complex Hilbert space H when an additional semi-inner product structure defined by a positive (semi-definite) operator A on H is considered.
Najla Altwaijry, Kais Feki, Nicuşor Minculete   +2 more
doaj   +1 more source

On C-hyponormal operators

Journal of Mathematical Inequalities
Summary: A bounded linear operator \(T: \mathscr{H}\rightarrow\mathscr{H}\) is a \(C\)-\textit{hyponormal} operator if \(T^\ast T - CTT^\ast C \geqslant 0\) for a conjugation \(C\) on \(\mathscr{H}\). In this paper, we study properties of \(C\)-hyponormal operators. Especially, we prove that for \(\mathscr{M}\in\mathrm{Lat}(T)\) and a conjugation \(C =
Ko, Eungil, Lee, Ji Eun, Lee, Mee-Jung
openaire   +2 more sources

The Near Subnormal Weighted Shift and Recursiveness

International Journal of Analysis, Volume 2013, Issue 1, 2013., 2013
We aim at studying the near subnormality of the unilateral weighted shifts, whose moment sequences are defined by linear recursive relations of finite order. Using the basic properties of recursive sequences, we provide a natural necessary condition, that ensure the near subnormality of this important class of weighted shifs.
R. Ben Taher, M. Rachidi, Chuanxi Qian
wiley   +1 more source

Structure of Iso-Symmetric Operators

Axioms, 2021
For a Hilbert space operator T∈B(H), let LT and RT∈B(B(H)) denote, respectively, the operators of left multiplication and right multiplication by T. For positive integers m and n, let ▵T∗,Tm(I)=(LT∗RT−I)m(I) and δT∗,Tn(I)=(LT∗−RT)m(I).
Bhagwati Prashad Duggal, In-Hyoun Kim
doaj   +1 more source

Similarity of C1: Operators and the Hyperinvariant Subspace Problem

Journal of Mathematics, Volume 2024, Issue 1, 2024.
In the present paper, we first show that the existence of the solutions of the operator equation S∗XT = X is related to the similarity of operators of class C1., and then we give a sufficient condition for the existence of nontrivial hyperinvariant subspaces. These subspaces are the closure of ranφ(T) for some singular inner functions φ.
Abdelkader Segres, Ahmed Bachir, Sid Ahmed Ould Ahmed Mahmoud, G. Muhiuddin   +3 more
wiley   +1 more source

More on (α, β)‐Normal Operators in Hilbert Spaces

Abstract and Applied Analysis, Volume 2012, Issue 1, 2012., 2012
We study some properties of (α, β)‐normal operators and we present various inequalities between the operator norm and the numerical radius of (α, β)‐normal operators on Banach algebra ℬ(ℋ) of all bounded linear operators T : ℋ → ℋ, where ℋ is Hilbert space.
Rasoul Eskandari, Farzollah Mirzapour, Ali Morassaei, Gerd Teschke   +3 more
wiley   +1 more source