A Weak Generalize Localization of Multiple Fourier Series of Continuous Functions with a Certain Module of Continuity
I. L. Bloshanskiia,
T. A. Matseevichb a Moscow State Pedagogical University
b Moscow State University of Civil Engineering
Abstract:
Let
$E$ be an arbitrary measurable set,
$E\subset T^N=[-\pi,\pi)^N$,
$N\ge 1$,
$\mu E>0$, let
$\mu$ be a measure. In this paper, a weak generalize almost everywhere localization is studied, i.e., for given subsets
$E_1\subset E$,
$\mu E_1>0$ we study the almost everywhere convergence of multiple trigonometric Fourier series of functions those are zero on
$E$. We obtain sufficient conditions for the almost everywhere convergence of multiple Fourier series (summable over rectangles) of functions from
$H^\omega(T^N)$, $\omega(\delta)=o\left(\left[\log\dfrac1\delta\log\log\log\dfrac1\delta\right]^{-1}\right)$, as
$\delta\to0$ on
$E_1$. These conditions are given in terms of the sets'
$E_1$,
$E$ structure and geometry and related to certain orthogonal projections of the sets; they are called the
$\mathbb{B}_3$ property of the set
$E$. Formerly, one of the authors has introduced the
$\mathbb B_k$,
$k=1,2$ properties of the set
$E$, which are related to one-dimensional and two-dimensional projections of the sets
$E$ and
$E_1$ respectively, as sufficient conditions for the almost everywhere convergence of Fourier series of functions from
$L_1(T^N)$ and
$L_p(T^N)$,
$p>1$. The presented results generalize these ideas.
UDC:
517.5