Buscar
Mostrando ítems 1-10 de 582
Inequalities in Lp−1 for the extended Lp best approximation operator
(Elsevier Inc, 2012-09)
The best polynomial approximation operator was recently extended by one of the authors from Lp to Lp−1. In this paper, we study weak and strong inequalities for maximal operators related with the extended best polynomial ...
Best approximation by diagonal compact operators
(Elsevier Science Inc, 2013-09)
We study the existence and characterization properties of compact Hermitian operators C on a Hilbert space H such that the norm of C is less or equal to that of C + D , for all the real and compact diagonals D in a fixed ...
A characterization of the extended best φ-approximation operator
(Taylor & Francis, 2011-05)
Given an non necessarily linear operator T defined from an Orlicz space L φ′(Ω, , μ) into itself, where φ′ denote the derivative of a strictly convex function φ, we give necessary and sufficient conditions on T assuring ...
Extended best polynomial approximation operator in Orlicz Spaces
(Taylor & Francis, 2015-04)
In this article we consider the best polynomial approximation operator, defined in an Orlicz space L Φ(B), and its extension to L ϕ(B) where ϕ is the derivative function of Φ. A characterization of these operators and ...
Maximal inequalities for a best approximation operator in Orlicz spaces
(Adam Mickiewicz University in Poznań. Faculty of Mathematics and Computer Sciences, 2011-08)
In this paper we study a maximal operator Mf related with the best ϕ approximation by constants for a function f ∈ L ϕ 0 loc(ℝn), where we denote by ϕ 0 for the derivative function of the C1 convex function ϕ. We get a ...
Existence and characterization of best φ-approximations by linear subspaces
(Walter de Gruyter GmbH, 2017-07)
Given an Orlicz space Lφ, we give very relaxed sufficient conditions on φ to ensure that there exists a best φ-approximation from any finite dimensional bounded linear subspace S ⊂ Lφ. In addition, given an operator T, ...
Inequalities for the Extended Best Polynomial Approximation Operator in Orlicz Spaces
(Springer Heidelberg, 2019-02)
In this paper we pursue the study of the best approximation operator extended from L^Φ to L^φ, where φ denotes the derivative of the function Φ. We get pointwise convergence for the coefficients of the extended best ...
On a conjecture by Mbekhta about best approximation by polar factors
(American Mathematical Society, 2021-11)
The polar factor of a bounded operator acting on a Hilbert space is the unique partial isometry arising in the polar decomposition. It is well known that the polar factor might not be a best approximant to its associated ...
Extension of the Best Constant Approximation Operator in Orlicz Spaces
(Taylor & Francis, 2020-04)
In this article we deal with the best φ-approximation operator by constants extended from an Orlicz space Lφ(Ω) to the space Lψ+ (Ω) where ψ+ denotes the right derivative of the function φ. We obtain pointwise convergence ...
Maximal Inequalities for the best polynomial approximation operators and Simonenko indices
(Global Science Journal, 2017-09)
In an abstract set up, we get strong type inequalities in L^p+1 by assuming weak or extra-weak inequalitie in Orlicz spaces. For some classes of functions, the number p is related to Simonenko indices. We apply the results ...