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Wyszukujesz frazę "bounded operators" wg kryterium: Temat


Wyświetlanie 1-12 z 12
Tytuł:
Multipliers of Hardy spaces, quadratic integrals and Foiaş-Williams-Peller operators
Autorzy:
Blower, G.
Powiązania:
https://bibliotekanauki.pl/articles/1217911.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
polynomially bounded operators
Hankel operators
multipliers
Carleson measures
Opis:
We obtain a sufficient condition on a B(H)-valued function φ for the operator $⨍ ↦ Γ_φ ⨍'(S)$ to be completely bounded on $H^∞ B(H)$; the Foiaş-Williams-Peller operator | S^t Γ_φ | R_φ = | | | 0 S | is then similar to a contraction. We show that if ⨍ : D → B(H) is a bounded analytic function for which $(1-r) ||⨍'(re^{iθ})||^2_{B(H)} rdrdθ$ and $(1-r) ||⨍"(re^{iθ})||_{B(H)} rdrdθ$ are Carleson measures, then ⨍ multiplies $(H^1c^1)'$ to itself. Such ⨍ form an algebra A, and when φ'∈ BMO(B(H)), the map $⨍ ↦ Γ_φ ⨍'(S)$ is bounded $A → B(H^2(H), L^2(H) ⊖ H^2(H))$. Thus we construct a functional calculus for operators of Foiaş-Williams-Peller type.
Źródło:
Studia Mathematica; 1998, 131, 2; 179-188
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An infinite dimensional Banach algebra with all but one maximal abelian subalgebras of dimension two
Autorzy:
Żelazko, Wiesław
Powiązania:
https://bibliotekanauki.pl/articles/960131.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
Abelian algebra
Bounded operators
Complex Banach space
Opis:
I construct a unital closed subalgebra of L(H) with the property announced in the title. Moreover, for any two maxiamal abelian subalgebras of the algebra in question, their intersection consists only of scalar multiples of the unity.
Źródło:
Commentationes Mathematicae; 2008, 48, 1
0373-8299
Pojawia się w:
Commentationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Maximal abelian subalgebras of \(B(\mathcal{X})\)
Autorzy:
Bračič, Janko
Kuzma, Bojan
Powiązania:
https://bibliotekanauki.pl/articles/746718.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
Abelian algebra
Bounded operators
Complex Banach space
Opis:
Let \(\mathcal{X}\) be an infinite dimensional complex Banach space and \(B(\mathcal{X})\) be the Banach algebra of all bounded linear operators on \(\mathcal{X}\). Żelazko [1] posed the following question: Is it possible that some maximal abelian subalgebra of \(B(\mathcal{X})\) is finite dimensional? Interestingly, he was able to show that there does exist an infinite dimensional closed subalgebra of \(B(\mathcal{X})\) with all but one maximal abelian subalgebras of dimension two. The aim of this note is to give a negative answer to the original question and prove that there does not exist a finite dimensional maximal commutative subalgebra of \(B(\mathcal{X})\) if \(\text{dim} X = \infty\).
Źródło:
Commentationes Mathematicae; 2008, 48, 1
0373-8299
Pojawia się w:
Commentationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On operators with unitary ϱ-dilations
Autorzy:
Ando, T.
Takahashi, K.
Powiązania:
https://bibliotekanauki.pl/articles/1294732.pdf
Data publikacji:
1997
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
polynomially bounded operators
operators of class $C_ϱ$
unitary ϱ-dilation
Opis:
We show a polynomially boundend operator T is similar to a unitary operator if there is a singular unitary operator W and an injection X such that XT = WX. If, in addition, T is of class $C_ϱ$, then T itself is unitary.
Źródło:
Annales Polonici Mathematici; 1997, 66, 1; 11-14
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Volterra integral operators on a family of Dirichlet-Morrey spaces
Autorzy:
Hu, Lian
Liu, Xiaosong
Powiązania:
https://bibliotekanauki.pl/articles/29519523.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Dirichlet-Morrey type space
Carleson measure
Volterra integral operators
bounded operators
essential norm
Opis:
A family of Dirichlet-Morrey spaces $ \mathcal{D}_{\lambda,K} $ of functions analytic in the open unit disk $ \mathbb{D} $ are defined in this paper. We completely characterize the boundedness of the Volterra integral operators $ T_g, I_g $ and the multiplication operator $ M_g $ on the space $ \mathcal{D}_{\lambda,K} $. In addition, the compactness and essential norm of the operators $ T_g $ and $ I_g $ on $ \mathcal{D}_{\lambda,K} $ are also investigated.
Źródło:
Opuscula Mathematica; 2023, 43, 5; 633-649
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Putnam-Fuglede property for paranormal and *-paranormal operators
Autorzy:
Pagacz, P.
Powiązania:
https://bibliotekanauki.pl/articles/254725.pdf
Data publikacji:
2013
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
power-bounded operators
paranormal operators
*-paranormal operators
k-paranormal operators
k*-paranormal operators
Putnam-Fuglede theorem
Opis:
An operator T ∈ B(H) is said to have the Putnam-Fuglede commutativity property (PF property for short) if T*X = XJ for any X ∈ B(K,H) and any isometry J ∈ B(K) such that TX = XJ*. The main purpose of this paper is to examine if paranormal operators have the PF property. We prove that k*-paranormal operators have the PF property. Furthermore, we give an example of a paranormal without the PF property.
Źródło:
Opuscula Mathematica; 2013, 33, 3; 565-574
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Weakly precompact operators on $C_{b}(X,E)$ with the strict topology
Autorzy:
Stochmal, Juliusz
Powiązania:
https://bibliotekanauki.pl/articles/729586.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
spaces of vector-valued continuous functions
strict topologies
operator measures
strongly bounded operators
weakly precompact operators
Opis:
Let X be a completely regular Hausdorff space, E and F be Banach spaces. Let $C_{b}(X,E)$ be the space of all E-valued bounded continuous functions on X, equipped with the strict topology β. We study weakly precompact operators $T:C_{b}(X,E) → F$. In particular, we show that if X is a paracompact k-space and E contains no isomorphic copy of l¹, then every strongly bounded operator $T:C_{b}(X,E) → F$ is weakly precompact.
Źródło:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2016, 36, 1; 65-77
1509-9407
Pojawia się w:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On invariant measures for power bounded positive operators
Autorzy:
Sato, Ryotaro
Powiązania:
https://bibliotekanauki.pl/articles/1287342.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
power bounded and Cesàro bounded positive operators
invariant measures
$L_1$ spaces
Opis:
We give a counterexample showing that $\overline{(I-T*)L_{∞}} ∩ L^{+}_{∞} = {0}$ does not imply the existence of a strictly positive function u in $L_1$ with Tu = u, where T is a power bounded positive linear operator on $L_1$ of a σ-finite measure space. This settles a conjecture by Brunel, Horowitz, and Lin.
Źródło:
Studia Mathematica; 1996, 120, 2; 183-189
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On \(C^{(n)}\)-Almost Periodic Solutions to Some Nonautonomous Differential Equations in Banach Spaces
Autorzy:
Baillon, Jean-Bernard
Blot, Joël
N'Guérékata, Gaston M.
Pennequin, Denis
Powiązania:
https://bibliotekanauki.pl/articles/746570.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
\(C^{(n)}\)-almost periodic function
family of bounded operators
exponentially stable
Acquistapace-Terreni conditions
uniform spectrum of bounded functions
Opis:
In this paper we prove the existence and uniqueness of \(C^{(n)}\)-almost periodic solutions to the nonautonomous ordinary differential equation \(x'(t) = A(t)x(t) + f(t)\), \(t\in\mathbb{R}\), where \(A(t)\) generates an exponentially stable family of operators \((U (t, s))\) \(t\geq s\) and \(f\) is a \(C^{(n)}\)-almost periodic function with values in a Banach space \(X\). We also study a Volterra-like equation with a \(C^{(n)}\)-almost periodic solution.
Źródło:
Commentationes Mathematicae; 2006, 46, 2
0373-8299
Pojawia się w:
Commentationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bounded projections in weighted function spaces in a generalized unit disc
Autorzy:
Karapetyan, A.
Powiązania:
https://bibliotekanauki.pl/articles/1311367.pdf
Data publikacji:
1995
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
generalized unit disc
holomorphic and pluriharmonic functions
weighted spaces
integral representations
bounded integral operators
Opis:
Let $M_{m,n}$ be the space of all complex m × n matrices. The generalized unit disc in $M_{m,n}$ is $R_{m,n} = {Z ∈ M_{m,n}: I^{(m)} - ZZ^\ast \text{ is positive definite} }$. Here $I^{(m)} ∈ M_{m,m}$ is the unit matrix. If 1 ≤ p < ∞ and α > -1, then $L_{α}^{p}(R_{m,n})$ is defined to be the space $L^p{R_{m,n}; [det(I^{(m)} - ZZ^\ast)]^α dμ_{m,n}(Z)}$, where $μ_{m,n}$ is the Lebesgue measure in $M_{m,n}$, and $H_α^p(R_{m,n}) ⊂ L_{α}^{p}(R_{m,n})$ is the subspace of holomorphic functions. In [8,9] M. M. Djrbashian and A. H. Karapetyan proved that, if $Reβ > (α+1)//p -1$ (for 1 < p < ∞) and Re β ≥ α (for p = 1), then $f(\mathcal{Z})= T_{m,n}^{β}(f)(\mathcal{Z}), \mathcal{Z} ∈ R_{m,n},$ where $T_{m,n}^{β}$ is the integral operator defined by (0.13)-(0.14). In the present paper, given 1 ≤ p < ∞, we find conditions on α and β for $T_{m,n}^{β}$ to be a bounded projection of $L_α^p(R_{m,n})$ onto $H_α^p(R_{m,n})$. Some applications of this result are given.
Źródło:
Annales Polonici Mathematici; 1995, 62, 3; 193-218
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Weak compactness in the space of operator valued measures $M_ba(Σ,(X,Y))$ and its applications
Autorzy:
Ahmed, N.
Powiązania:
https://bibliotekanauki.pl/articles/729361.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
space of operator valued measures
weak compactness
semigroups of bounded linear operators
optimal structural control
Opis:
In this note we present necessary and sufficient conditions characterizing conditionally weakly compact sets in the space of (bounded linear) operator valued measures $M_{ba}(Σ,(X,Y))$. This generalizes a recent result of the author characterizing conditionally weakly compact subsets of the space of nuclear operator valued measures $M_{ba}(Σ,₁(X,Y))$. This result has interesting applications in optimization and control theory as illustrated by several examples.
Źródło:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2011, 31, 2; 231-247
1509-9407
Pojawia się w:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Order bounded composition operators on the Hardy spaces and the Nevanlinna class
Autorzy:
Jaoua, Nizar
Powiązania:
https://bibliotekanauki.pl/articles/1217094.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
composition operators
order bounded maps
Hardy spaces
Nevanlinna class
radial limit
moment sequences and analytic moment sequences
Opis:
We study the order boundedness of composition operators induced by holomorphic self-maps of the open unit disc D. We consider these operators first on the Hardy spaces $H^p$ 0 < p < ∞ and then on the Nevanlinna class N. Given a non-negative increasing function h on [0,∞[, a composition operator is said to be X,L_h-order bounded (we write (X,L_h)-ob) with $X = H^p$ or X = N if its composition with the map f ↦ f*, where f* denotes the radial limit of f, is order bounded from X into $L_h$. We give a complete characterization and a family of examples in both cases. On the other hand, we show that the ($N,log^{+}L$)-ob composition operators are exactly those which are Hilbert-Schmidt on $H^2$. We also prove that the ($N,L^q$)-ob composition operators are exactly those which are compact from N into $H^q$.
Źródło:
Studia Mathematica; 1999, 134, 1; 35-55
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-12 z 12

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