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Wyszukujesz frazę "continuous operators" wg kryterium: Temat


Wyświetlanie 1-10 z 10
Tytuł:
A general differentiation theorem for superadditive processes
Autorzy:
Sato, Ryotaro
Powiązania:
https://bibliotekanauki.pl/articles/965787.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
differentiation theorem
superadditive process
absolutely continuous norm
local ergodic theorem
semigroup of positive linear operators
Banach lattice of functions
Opis:
Let L be a Banach lattice of real-valued measurable functions on a σ-finite measure space and T={$T_t$: t < 0} be a strongly continuous semigroup of positive linear operators on the Banach lattice L. Under some suitable norm conditions on L we prove a general differentiation theorem for superadditive processes in L with respect to the semigroup T.
Źródło:
Colloquium Mathematicum; 2000, 83, 1; 125-136
0010-1354
Pojawia się w:
Colloquium Mathematicum
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Extension Gevrey et rigidité dans un secteur
Autorzy:
Thilliez, Vincent
Powiązania:
https://bibliotekanauki.pl/articles/1288536.pdf
Data publikacji:
1995
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Gevrey classes
continuous extension operators
sequences of uniqueness
rigidity
Opis:
We study a rigidity property, at the vertex of some plane sector, for Gevrey classes of holomorphic functions in the sector. For this purpose, we prove a linear continuous version of Borel-Ritt's theorem with Gevrey conditions
Źródło:
Studia Mathematica; 1995-1996, 117, 1; 29-41
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On one condition of absolutely continuous spectrum for self-adjoint operators and its applications
Autorzy:
Ianovich, E.
Powiązania:
https://bibliotekanauki.pl/articles/254841.pdf
Data publikacji:
2018
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
self-adjoint operators absolutely continuous spectrum
equi-absolute continuity
spectral density
Jacobi matrices
Opis:
In this work the method of analyzing of the absolutely continuous spectrum for self-adjoint operators is considered. For the analysis it is used an approximation of a self-adjoint operator A by a sequence of operators An with absolutely continuous spectrum on a given interval [a, b] which converges to A in a strong sense on a dense set. The notion of equi-absolute continuity is also used. It was found a sufficient condition of absolute continuity of the operator A spectrum on the finite interval [a, b] and the condition for that the corresponding spectral density belongs to the class Lp[a,b] (p ≥ 1). The application of this method to Jacobi matrices is considered. As one of the results we obtain the following assertion: Under some mild assumptions, suppose that there exist a constant C > 0 and a positive function g(x) ∈ Lp[a, b] (p ≥ 1).such that for all n sufficiently large and almost all [formula] the estimate [formula] holds, where Pn(x) are 1st type polynomials associated with Jacobi matrix (in the sense of Akhiezer) and bn is a second diagonal sequence of Jacobi matrix. Then the spectrum of Jacobi matrix operator is purely absolutely continuous on [a, b] and for the corresponding spectral density ƒ (x) we have ƒ (x) ∈ Lp[a,b].
Źródło:
Opuscula Mathematica; 2018, 38, 5; 699-718
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On operator ideals related to (p,σ)-absolutely continuous operators
Autorzy:
López Molina, J. A.
Sánchez Pérez, E. A.
Powiązania:
https://bibliotekanauki.pl/articles/1206151.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
tensor norms
operator ideals
(p,σ)-absolutely continuous operators
$g_{p,σ}$-nuclear and $g_{p,σ}$ integral operators
Opis:
We study tensor norms and operator ideals related to the ideal $P_{p,σ}$, 1 < p < ∞, 0 < σ < 1, of (p,σ)-absolutely continuous operators of Matter. If α is the tensor norm associated with $P_{p,σ}$ (in the sense of Defant and Floret), we characterize the $(α')^t$-nuclear and $(α')^t$- integral operators by factorizations by means of the composition of the inclusion map $L^r(μ) → L^1(μ) + L^p(μ)$ with a diagonal operator $B_w:L^{∞}(μ) → L^r(μ)$, where r is the conjugate exponent of p'/(1-σ). As an application we study the reflexivity of the components of the ideal $P_{p,σ}$.
Źródło:
Studia Mathematica; 2000, 138, 1; 25-40
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Singular continuous spectrum of half-line Schrodinger operators with point interactions on a sparse set
Autorzy:
Lotoreichik, V.
Powiązania:
https://bibliotekanauki.pl/articles/254871.pdf
Data publikacji:
2011
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
half-line Schrodinger operators
delta-interactions
singular continuous spectrum
Opis:
We say that a discrete set X = {xn}n ∈ N0 on the half-line 0 = x0 < x1 < x2 < x3 < ⋅ ⋅ ⋅< xn < ⋅ ⋅ ⋅,< +∞ is sparse if the distances Δxn = xn+1-xn between neighbouring points satisfy the condition [formula]. In this paper half-line Schrödinger operators with point δ- and δ'- interactions on a sparse set are considered. Assuming that strengths of point interactions tend to ∞ we give simple sufficient conditions for such Schrödinger operators to have non-empty singular continuous spectrum and to have purely singular continuous spectrum, which coincides with R+.
Źródło:
Opuscula Mathematica; 2011, 31, 4; 615-628
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spontaneous decay of level from spectral theory point of view
Autorzy:
Ianovich, Eduard
Powiązania:
https://bibliotekanauki.pl/articles/2048989.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
spectral theory
quantum field theory
self-adjoint operators
absolutely continuous spectrum
spontaneous decay
Opis:
In quantum field theory it is believed that the spontaneous decay of excited atomic or molecular level is due to the interaction with continuum of field modes. Besides, the atom makes a transition from upper level to lower one so that the probability to find the atom in the excited state tends to zero. In this paper it will be shown that the mathematical model in single-photon approximation may predict another behavior of this probability generally. Namely, the probability to find the atom in the excited state may tend to a nonzero constant so that the atom is not in the pure state finally. This effect is due to that the spectrum of the complete Hamiltonian is not purely absolutely continuous and has a discrete level outside the continuous part. Namely, we state that in the corresponding invariant subspace, determining the time evolution, the spectrum of the complete Hamiltonian when the field is considered in three dimensions may be not purely absolutely continuous and may have an eigenvalue. The appearance of eigenvalue has a threshold character. If the field is considered in two dimensions the spectrum always has an eigenvalue and the decay is absent.
Źródło:
Opuscula Mathematica; 2021, 41, 6; 849-859
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stabilité du spectre ponctuel dopérateurs de Toeplitz généralisés
Autorzy:
Nikolskaia, Lioudmila
Powiązania:
https://bibliotekanauki.pl/articles/1288866.pdf
Data publikacji:
1995
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Toeplitz and Wiener-Hopf operators
multipliers
quasi-continuous functions
Opis:
A general scheme based on a commutation relation is proposed to give rise to a definition of generalized Toeplitz operators on a Banach space. Under suitable conditions the existence of a symbol is proved and its continuation to algebras generated by generalized Toeplitz operators is constructed. A stability theorem for the point spectrum of an operator from generalized Toeplitz algebras is established; as examples one considers the standard and operator valued Toeplitz operators on weighted Hardy spaces and on spaces of functions (distributions) with weighted $l^p$ Fourier transforms.
Źródło:
Studia Mathematica; 1995, 116, 1; 1-22
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Topological properties of some spaces of continuous operators
Autorzy:
Nowak, Marian
Powiązania:
https://bibliotekanauki.pl/articles/729596.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
spaces of vector-valued continuous functions
strict topologies
operator measures
topology of simple convergence
continuous 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 topological properties of the space $L_{β}(C_{b}(X,E),F)$ of all $(β,||·||_{F})$-continuous linear operators from $C_{b}(X,E)$ to F, equipped with the topology $τ_{s}$ of simple convergence. If X is a locally compact paracompact space (resp. a P-space), we characterize $τ_{s}$-compact subsets of $L_{β}(C_{b}(X,E),F)$ in terms of properties of the corresponding sets of the representing operator-valued Borel measures. It is shown that the space $(L_{β}(C_{b}(X,E),F),τ_{s})$ is sequentially complete if X is a locally compact paracompact space.
Źródło:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2016, 36, 1; 79-86
1509-9407
Pojawia się w:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Uniformly continuous composition operators in the space of bounded Φ-variation functions in the Schramm sense
Autorzy:
Ereu, T.
Merentes, N.
Sanchez, J. L.
Wróbel, M.
Powiązania:
https://bibliotekanauki.pl/articles/255979.pdf
Data publikacji:
2012
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Phi-variation in the sense of Schramm
uniformly continuous operator
regularization
composition operator
Jensen equation
locally defined operators
Opis:
We prove that any uniformly continuous Nemytskii composition operator in the space of functions of bounded generalized Φ-variation in the Schramm sense is affine. A composition operator is locally defined. We show that every locally defined operator mapping the space of continuous functions of bounded (in the sense of Jordan) variation into the space of continous monotonic functions is constant.
Źródło:
Opuscula Mathematica; 2012, 32, 2; 239-247
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
    Wyświetlanie 1-10 z 10

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