A Bohr-Nikol’skii Inequality for Weighted Lebesgue Spaces

2019 ◽  
Vol 44 (3) ◽  
pp. 701-710
Author(s):  
Ha Huy Bang ◽  
Vu Nhat Huy
Author(s):  
H.H. Bang ◽  
V. N. Huy

In this paper, we give some results concerning Bernstein--Nikol'skii inequality for weighted Lebesgue spaces. The main result is as follows: Let $1 < u,p < \infty$, $0<q+ 1/p <v + 1/u <1,$ $v-q\geq 0$, $\kappa >0$, $f \in L^u_v(\R)$ and $\supp\widehat{f} \subset [-\kappa, \kappa]$. Then $D^mf \in L^p_q(\R)$, $\supp\widehat{D^m f}=\supp\widehat{f}$ and there exists a~constant~$C$ independent of $f$, $m$, $\kappa$ such that $\|D^mf\|_{L^p_{q}} \leq C m^{-\varrho} \kappa^{m+\varrho} \|f\|_{ L^u_v}, $ for all $m = 1,2,\dots $, where $\varrho=v + \frac{1}{u} -\frac{1}{p} - q>0,$ and the weighted Lebesgue space $L^p_q$ consists of all measurable functions such that $\|f\|_{L^p_q} = \big(\int_{\R} |f(x)|^p |x|^{pq} dx\big)^{1/p} < \infty.$ Moreover, $ \lim_{m\to \infty}\|D^mf\|_{L^p_{q}}^{1/m}= \sup \big\{ |x|: \, x \in \textnormal{supp}\widehat{f}\big \}.$ The~advantage of our result is that $m^{-\varrho}$ appears on the right hand side of the inequality ($\varrho >0$), which has never appeared in related articles by other authors. The corresponding result for the $n$-dimensional case is also obtained.


2012 ◽  
Vol 364 (3) ◽  
pp. 1163-1177 ◽  
Author(s):  
Daewon Chung ◽  
M. Cristina Pereyra ◽  
Carlos Perez

2013 ◽  
Vol 2013 ◽  
pp. 1-13
Author(s):  
Pedro J. Miana ◽  
Juan J. Royo ◽  
Luis Sánchez-Lajusticia

The main aim of this paper is to show that certain Banach spaces, defined via integral kernel operators, are Banach modules (with respect to some known Banach algebras and convolution products onℝ+). To do this, we consider some suitable kernels such that the Hardy-type operator is bounded in weighted Lebesgue spacesLωpℝ+forp≥1. We also show new inequalities in these weighted Lebesgue spaces. These results are applied to several concrete function spaces, for example, weighted Sobolev spaces and fractional Sobolev spaces defined by Weyl fractional derivation.


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