A Littlewood--Paley type theorem and a~corollary
Izvestiya. Mathematics , Tome 77 (2013) no. 6, pp. 1155-1194
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We prove an analogue of the Littlewood–Paley theorem for orthoprojectors
onto mutually orthogonal subspaces of piecewise-polynomial functions
on the cube $I^d$. This yields upper bounds for the norms of functions
in $L_p(I^d)$ in terms of the corresponding norms of the projections
to subspaces of piecewise-polynomial functions of several variables.
We use these results to obtain upper bounds for the Kolmogorov widths
of Besov classes of (non-periodic) functions satisfying mixed
Hölder conditions.
Keywords:
orthoprojector, mutually orthogonal subspaces,
piecewise-polynomial functions, Littlewood–Paley theorem, width.
@article{IM2_2013_77_6_a3,
author = {S. N. Kudryavtsev},
title = {A {Littlewood--Paley} type theorem and a~corollary},
journal = {Izvestiya. Mathematics },
pages = {1155--1194},
publisher = {mathdoc},
volume = {77},
number = {6},
year = {2013},
language = {en},
url = {http://geodesic.mathdoc.fr/item/IM2_2013_77_6_a3/}
}
S. N. Kudryavtsev. A Littlewood--Paley type theorem and a~corollary. Izvestiya. Mathematics , Tome 77 (2013) no. 6, pp. 1155-1194. http://geodesic.mathdoc.fr/item/IM2_2013_77_6_a3/