%0 Journal Article
%T On sets of large exponential sums
%A I. D. Shkredov
%J Mathematics
%D 2006
%I arXiv
%X Let A be a subset of Z / NZ, and let R be the set of large Fourier coefficients of A. Properties of R have been studied in works of M.-C. Chang and B. Green. Our result is the following : the number of quadruples (r_1, r_2, r_3, r_4) \in R^4 such that r_1 + r_2 = r_3 + r_4 is at least |R|^{2+\epsilon}, \epsilon>0. This statement shows that the set R is highly structured. We also discuss some of the generalizations and applications of our result.
%U http://arxiv.org/abs/math/0605689v1