By a Fourier multiplier technique on Cantor-like Abelian groups with characters of finite order, the norms from L² into of certain embeddings of character sums are computed. It turns out that the orders of the characters are immaterial as soon as they are at least four.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm87-1-2,
author = {Mats Erik Andersson},
title = {Two examples of subspaces in $L^{2l}$ spanned by characters of finite order},
journal = {Colloquium Mathematicae},
volume = {89},
year = {2001},
pages = {13-26},
zbl = {0983.43001},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm87-1-2}
}
Mats Erik Andersson. Two examples of subspaces in $L^{2l}$ spanned by characters of finite order. Colloquium Mathematicae, Tome 89 (2001) pp. 13-26. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm87-1-2/