Results 41 to 50 of about 1,973 (103)

Sobolev type inequalities in ultrasymmetric spaces with applications to Orlicz‐Sobolev embeddings

Journal of Function Spaces, Volume 3, Issue 2, Page 183-208, 2005., 2005
Let Dkf mean the vector composed by all partial derivatives of order k of a function f(x), x ∈ Ω ⊂ ℝn. Given a Banach function space A, we look for a possibly small space B such that ‖f‖B≤c‖|Dkf|‖A for all f∈C0k(Ω). The estimates obtained are applied to ultrasymmetric spaces A = Lφ,E, B = Lψ,E, giving some optimal (or rather sharp) relations between ...
Evgeniy Pustylnik, Lech Maligranda
wiley   +1 more source

Domains of pseudo‐differential operators: a case for the Triebel‐Lizorkin spaces

Journal of Function Spaces, Volume 3, Issue 3, Page 263-286, 2005., 2005
The main result is that every pseudo‐differential operator of type 1, 1 and order d is continuous from the Triebel‐Lizorkin space Fp,1d to Lp, 1 ≤ p≺∞, and that this is optimal within the Besov and Triebel‐Lizorkin scales. The proof also leads to the known continuity for s≻d, while for all real s the sufficiency of Hörmander′s condition on the twisted ...
Jon Johnsen, Victor Burenkov
wiley   +1 more source

Box dimension, oscillation and smoothness in function spaces

Journal of Function Spaces, Volume 3, Issue 3, Page 287-320, 2005., 2005
The aim of this paper is twofold. First we relate upper and lower box dimensions with oscillation spaces, and we develop embeddings or inclusions between oscillation spaces and Besov spaces. Secondly, given a point in the (1p, s)‐plane we determine maximal and minimal values for the upper box dimension (also the maximal value for lower box dimension ...
Abel Carvalho, Hans Triebel
wiley   +1 more source

Results on existence for generalized nD Navier-Stokes equations

Open Mathematics, 2019
In this paper we consider a class of nD Navier-Stokes equations of Kirchhoff type and prove the global existence of solutions by using a new approach introduced in [Jday R., Zennir Kh., Georgiev S.G., Existence and smoothness for new class of n ...
Zennir Khaled
doaj   +1 more source

Multiplicity of solutions for a class of critical Schrödinger-Poisson systems on the Heisenberg group

Open Mathematics, 2023
We deal with multiplicity of solutions to the following Schrödinger-Poisson-type system in this article: ΔHu−μ1ϕ1u=∣u∣2u+Fu(ξ,u,v),inΩ,−ΔHv+μ2ϕ2v=∣v∣2v+Fv(ξ,u,v),inΩ,−ΔHϕ1=u2,−ΔHϕ2=v2,inΩ,ϕ1=ϕ2=u=v=0,on∂Ω,\left\{\begin{array}{ll}{\Delta }_{H}u-{\mu }_{1}{
Li Shiqi, Song Yueqiang
doaj   +1 more source

An embedding result

, 2013
In unbounded subset $\Omega$ in $R^n$ we study the operator $u\rightarrow gu$ as an operator defined in the Sobolev space $W^{r,p}(\Omega)$ and which takes values in $L^p(\Omega)$.
Canale, Anna
core   +1 more source

A sharpness result for powers of Besov functions

Journal of Function Spaces, Volume 2, Issue 3, Page 267-277, 2004., 2004
A recent result of Kateb asserts that f∈Bp,qs(ℝn) implies |f|μ∈Bp,qs(ℝn) as soon as the following three conditions hold: (1) 0≺s≺μ + (1/p), (2) f is bounded, (3) μ≻1. By means of counterexamples, we prove that those conditions are optimal.
Gérard Bourdaud, Jürgen Appell
wiley   +1 more source

Optimal order yielding discrepancy principle for simplified regularization in Hilbert scales: finite‐dimensional realizations

International Journal of Mathematics and Mathematical Sciences, Volume 2004, Issue 37, Page 1973-1996, 2004., 2004
Simplified regularization using finite‐dimensional approximations in the setting of Hilbert scales has been considered for obtaining stable approximate solutions to ill‐posed operator equations. The derived error estimates using an a priori and a posteriori choice of parameters in relation to the noise level are shown to be of optimal order with ...
Santhosh George, M. Thamban Nair
wiley   +1 more source

The Lusin Theorem and Horizontal Graphs in the Heisenberg Group

Analysis and Geometry in Metric Spaces, 2013
In this paper we prove that every collection of measurable functions fα , |α| = m, coincides a.e. withmth order derivatives of a function g ∈ Cm−1 whose derivatives of order m − 1 may have any modulus of continuity weaker than that of a Lipschitz ...
Hajłasz Piotr, Mirra Jacob
doaj   +1 more source

On functional reproducing kernels

Open Mathematics, 2023
We show that even if a Hilbert space does not admit a reproducing kernel, there could still be a kernel function that realizes the Riesz representation map.
Zhou Weiqi
doaj   +1 more source