Sökning: "Lorentz spaces"

Visar resultat 1 - 5 av 11 avhandlingar innehållade orden Lorentz spaces.

1. 1. Forever Young : Convolution Inequalities in Weighted Lorentz-type Spaces

   Författare :Martin Křepela; Sorina Barza; Javier Soria; Karlstads universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Convolution; Young inequality; Lorentz spaces; weights; rearrangement-invariant spaces; Matematik; Mathematics;

   Sammanfattning : This thesis is devoted to an investigation of boundedness of a general convolution operator between certain weighted Lorentz-type spaces with the aim of proving analogues of the Young convolution inequality for these spaces.Necessary and sufficient conditions on the kernel function are given, for which the convolution operator with the fixed kernel is bounded between a certain domain space and the weighted Lorentz space of type Gamma. LÄS MER

3. 2. Embedding Theorems for Mixed Norm Spaces and Applications

   Författare :Robert Algervik; Viktor Kolyada; Javier Soria; Karlstads universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; mixed norms; rearrangements; modulus of continuity; embeddings; Sobolev spaces; Besov spaces; Lorentz spaces; Mathematical analysis; Analys; Matematik; Mathematics;

   Sammanfattning : This thesis is devoted to the study of mixed norm spaces that arise in connection with embeddings of Sobolev and Besov type spaces. We study different structural, integrability, and smoothness properties of functions satisfying certain mixed norm conditions. Conditions of this type are determined by the behaviour of linear sections of functions. LÄS MER

4. 3. The Weighted Space Odyssey

   Författare :Martin Křepela; Sorina Barza; Gord Sinnamon; Karlstads universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; integral operators; supremal operators; weights; weighted function spaces; Lorentz spaces; Lebesgue spaces; convolution; Hardy inequality; multilinear operators; nonincreasing rearrangement; Matematik; Mathematics;

   Sammanfattning : The common topic of this thesis is boundedness of integral and supremal operators between weighted function spaces.The first type of results are characterizations of boundedness of a convolution-type operator between general weighted Lorentz spaces. LÄS MER

5. 4. Relations between functions from some Lorentz type spaces and summability of their Fourier coefficients

   Författare :Aigerim Kopezhanova; Natasha Samko; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Lorentz spaces; Fourier series; Inequalities; Mathematics; Matematik; Mathematics; Matematik;

   Sammanfattning : This Licentiate Thesis is devoted to the study of summability of the Fourier coefficients for functions from some Lorentz type spaces and contains three papers (papers A - C) together with an introduction, which put these papers into a general frame.Let $\Lambda_p(\omega),\;\; p>0,$ denote the Lorentz spaces equipped with the (quasi) norm$$\|f\|_{\Lambda_p(\omega)}:=\left(\int_0^1\left(f^*(t)\omega(t)\right)^p\frac{dt}{t}\right)^{\frac1p}$$for a function $f$ on [0,1] and with $\omega$ positive and equipped with some additional growth properties. LÄS MER

7. 5. Some new results concerning Lorentz sequence spaces and Schur multipliers : characterization of some new Banach spaces of infinite matrices

   Författare :Anca-Nicoleta Marcoci; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematics; Matematik;

   Sammanfattning : This Licentiate thesis consists of an introduction and three papers, which deal with some new spaces of infinite matrices and Lorentz sequence spaces.In the introduction we give an overview of the area that serves as a frame for the rest of the thesis. In particular, a short description of Schur multipliers is given. LÄS MER