and $d\ge2$. Similar approximation problems are considered for some other functions. Bibl. – 5 titles.
@article{ZNSL_2009_366_a0,
author = {A. B. Aleksandrov},
title = {Approximation in $L^p(\mathbb R^d)$, $0<p<1$, by linear combinations of the characteristic functions of balls},
journal = {Zapiski Nauchnykh Seminarov POMI},
pages = {5--12},
year = {2009},
volume = {366},
language = {ru},
url = {http://geodesic.mathdoc.fr/item/ZNSL_2009_366_a0/}
}
A. B. Aleksandrov. Approximation in $L^p(\mathbb R^d)$, $0
[1] A. B. Aleksandrov, “Essays on non locally convex Hardy classes”, Lecture Notes in Math., 864, 1981, 1–89 | DOI | MR | Zbl
[2] A B. Aleksandrov, “Spektralnye podprostranstva prostranstva $L^p$ pri $p1$”, Algebra i analiz, 19:3 (2007), 1–75 | MR
[3] Dzh. N. Vatson, Teoriya besselevykh funktsii, IL, M., 1949
[4] W. Rudin, Fourier analysis on groups, Reprint of the 1962 original, A Wiley-Interscience Publication, Wiley Classics Library, John Wiley and Sons, Inc., New York, 1990 | MR | Zbl
[5] I. Stein, G. Veis, Vvedenie v garmonicheskii analiz, Mir, M., 1974 | Zbl