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Wyszukujesz frazę "Riesz" wg kryterium: Temat


Wyświetlanie 1-10 z 10
Tytuł:
Distributional fractional powers of the Laplacean. Riesz potentials
Autorzy:
Martínez, Celso
Sanzi, Miguel
Periago, Francisco
Powiązania:
https://bibliotekanauki.pl/articles/1216946.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
fractional powers
Laplacean operator
Riesz potentials
singular integrals
Opis:
For different reasons it is very useful to have at one's disposal a duality formula for the fractional powers of the Laplacean, namely, $((-Δ)^α u,ϕ ) = (u,(-Δ)^α ϕ)$, α ∈ ℂ, for ϕ belonging to a suitable function space and u to its topological dual. Unfortunately, this formula makes no sense in the classical spaces of distributions. For this reason we introduce a new space of distributions where the above formula can be established. Finally, we apply this distributional point of view on the fractional powers of the Laplacean to obtain some properties of the Riesz potentials in a wide class of spaces which contains the $L^p$-spaces.
Źródło:
Studia Mathematica; 1999, 135, 3; 253-271
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Almost everywhere convergence of Laguerre series
Autorzy:
Chen, Chang-Pao
Lin, Chin-Cheng
Powiązania:
https://bibliotekanauki.pl/articles/1290468.pdf
Data publikacji:
1994
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
almost everywhere convergence
Cesàro means
Laguerre polynomials
Riesz means
Opis:
Let $a ∈ ℤ^+$ and $f ∈ L^p (ℝ^+), 1 ≤ p ≤ ∞ $. Denote by $c_j$ the inner product of f and the Laguerre function $ℒ^a_j$. We prove that if ${c_j}$ satisfies $lim_{λ↓1} \overline lim_{n→∞} ∑_{n
Źródło:
Studia Mathematica; 1994, 109, 3; 291-301
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Riesz means of Fourier transforms and Fourier series on Hardy spaces
Autorzy:
Weisz, Ferenc
Powiązania:
https://bibliotekanauki.pl/articles/1217804.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Hardy spaces
p-atom
atomic decomposition
interpolation
Fourier transforms
Riesz means
Opis:
Elementary estimates for the Riesz kernel and for its derivative are given. Using these we show that the maximal operator of the Riesz means of a tempered distribution is bounded from $H_p(ℝ)$ to $L_p(ℝ)$ (1/(α+1) < p < ∞) and is of weak type (1,1), where $H_p(ℝ)$ is the classical Hardy space. As a consequence we deduce that the Riesz means of a function $⨍ ∈ L_1(ℝ)$ converge a.e. to ⨍. Moreover, we prove that the Riesz means are uniformly bounded on $H_p(ℝ)$ whenever 1/(α+1) < p < ∞. Thus, in case $⨍ ∈ H_p(ℝ)$, the Riesz means converge to ⨍ in $H_p(ℝ)$ norm (1/(α+1) < p < ∞). The same results are proved for the conjugate Riesz means and for Fourier series of distributions.
Źródło:
Studia Mathematica; 1998, 131, 3; 253-270
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Almost everywhere summability of Laguerre series
Autorzy:
Stempak, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/1293496.pdf
Data publikacji:
1991
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Laguerre expansions
generalized twisted convolution
Riesz
Cesàro and Abel-Poisson means
Opis:
We apply a construction of generalized twisted convolution to investigate almost everywhere summability of expansions with respect to the orthonormal system of functions $ℓ_n^a(x) = (n!/Γ(n+a+1))^{1/2} e^{-x/2} L_n^a(x)$, n = 0,1,2,..., in $L^2(ℝ_+, x^adx)$, a ≥ 0. We prove that the Cesàro means of order δ > a + 2/3 of any function $f ∈ L^p(x^adx)$, 1 ≤ p ≤ ∞, converge to f a.e. The main tool we use is a Hardy-Littlewood type maximal operator associated with a generalized Euclidean convolution.
Źródło:
Studia Mathematica; 1991, 100, 2; 129-147
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On uniqueness of G-measures and g-measures
Autorzy:
Hua Fan, Ai
Powiązania:
https://bibliotekanauki.pl/articles/1287544.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
G-measures
g-measures
ergodic measures
Riesz products
quasi-invariance
dimension of measures
Opis:
We give a simple proof of the sufficiency of a log-lipschitzian condition for the uniqueness of G-measures and g-measures which were studied by G. Brown, A. H. Dooley and M. Keane. In the opposite direction, we show that the lipschitzian condition together with positivity is not sufficient. In the special case where the defining function depends only upon two coordinates, we find a necessary and sufficient condition. The special case of Riesz products is discussed and the Hausdorff dimension of Riesz products is calculated.
Źródło:
Studia Mathematica; 1996, 119, 3; 255-269
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sur les dimensions de mesures
Autorzy:
Hua Fan, Ai
Powiązania:
https://bibliotekanauki.pl/articles/1290182.pdf
Data publikacji:
1994
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
upper and lower dimension
dimension formulas
unidimensional
multifractal
Gibbs measure
Markov measure
Riesz product
Opis:
Firstly, we introduce the lower and upper dimensions for a measure defined on a metric space. Secondly, we establish the dimension formulas and characterize the unidimensional measures which were introduced by J.-P. Kahane. Lastly, we give some applications of these to the calculus of dimensions and the multifractal analysis of certain well known measures such as Lebesgue measures on Cantor sets, Gibbs measures, Markov measures and Riesz products etc.
Źródło:
Studia Mathematica; 1994, 111, 1; 1-17
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Complex Unconditional Metric Approximation Property for $C_{Λ}(\mathbb{T})$ spaces
Autorzy:
Li, Daniel
Powiązania:
https://bibliotekanauki.pl/articles/1220918.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Unconditional Metric Approximation Property
translation invariant spaces of continuous functions
Rosenthal set
Riesz set
linear invariant lifting
Opis:
We study the Complex Unconditional Metric Approximation Property for translation invariant spaces $C_{Λ}(\mathbb{T})$ of continuous functions on the circle group. We show that although some "tiny" (Sidon) sets do not have this property, there are "big" sets Λ for which $C_{Λ}(\mathbb{T})$ has (ℂ-UMAP); though these sets are such that $L_{Λ}^{∞}(\mathbb{T})$ contains functions which are not continuous, we show that there is a linear invariant lifting from these $L_{Λ}^{∞}(\mathbb{T})$ spaces into the Baire class 1 functions.
Źródło:
Studia Mathematica; 1996, 121, 3; 231-247
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Double exponential integrability, Bessel potentials and embedding theorems
Autorzy:
Edmunds, David E.
Gurka, Petr
Opic, Bohumír
Powiązania:
https://bibliotekanauki.pl/articles/1289003.pdf
Data publikacji:
1995
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Bessel potential
Riesz potential, generalized Lorentz-Zygmund spaces
exponential integrability
Hardy inequality
Orlicz spaces
Bessel potential spaces
Opis:
This paper is a continuation of [5] and provides necessary and sufficient conditions for double exponential integrability of the Bessel potential of functions from suitable (generalized) Lorentz-Zygmund spaces. These results are used to establish embedding theorems for Bessel potential spaces which extend Trudinger's result.
Źródło:
Studia Mathematica; 1995, 115, 2; 151-181
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measures and lacunary sets
Autorzy:
Lefèvre, Pascal
Powiązania:
https://bibliotekanauki.pl/articles/1216990.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
stationary sets
p-Sidon sets
sets of continuity
Λ(1) sets
Riesz sets
random Fourier series
(p,q)-summing operators
Opis:
We establish new connections between some classes of lacunary sets. The main tool is the use of (p,q)-summing or weakly compact operators (for Riesz sets). This point of view provides new properties of stationary sets and allows us to generalize to more general abelian groups than the torus some properties of p-Sidon sets. We also construct some new classes of Riesz sets.
Źródło:
Studia Mathematica; 1999, 133, 2; 145-161
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vector series whose lacunary subseries converge
Autorzy:
Drewnowski, Lech
Labuda, Iwo
Powiązania:
https://bibliotekanauki.pl/articles/1206244.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
subseries convergence
lacunary subseries
zero-density subseries
lacunary convergence property
topological Riesz space of measurable functions
topological vector space of Bochner measurable functions
Lebesgue property
Levi property
copy of $c_0$
Opis:
The area of research of this paper goes back to a 1930 result of H. Auerbach showing that a scalar series is (absolutely) convergent if all its zero-density subseries converge. A series $∑_n x_n$ in a topological vector space X is called ℒ-convergent if each of its lacunary subseries $∑_k x_{n_k}$ (i.e. those with $n_{k+1} - n_k → ∞$) converges. The space X is said to have the Lacunary Convergence Property, or LCP, if every ℒ-convergent series in X is convergent; in fact, it is then subseries convergent. The Zero-Density Convergence Property, or ZCP, is defined similarly though of lesser importance here. It is shown that for every ℒ-convergent series the set of all its finite sums is metrically bounded; however, it need not be topologically bounded. Next, a space with the LCP contains no copy of the space $c_0$. The converse holds for Banach spaces and, more generally, sequentially complete locally pseudoconvex spaces. However, an F-lattice of measurable functions is constructed that has both the Lebesgue and Levi properties, and thus contains no copy of $c_0$, and, nonetheless, lacks the LCP. The main (and most difficult) result of the paper is that if a Banach space E contains no copy of $c_0$ and λ is a finite measure, then the Bochner space $L_0$ (λ,e) has the LCP. From this, with the help of some Orlicz-Pettis type theorems proved earlier by the authors, the LCP is deduced for a vast class of spaces of (scalar and vector) measurable functions that have the Lebesgue type property and are "metrically-boundedly sequentially closed" in the containing $L_0$ space. Analogous results about the convergence of ℒ-convergent positive series in topological Riesz spaces are also obtained. Finally, while the LCP implies the ZCP trivially, an example is given that the converse is false, in general.
Źródło:
Studia Mathematica; 2000, 138, 1; 53-80
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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