English

A new bound for $A(A + A)$ for large sets

Number Theory 2023-02-09 v4

Abstract

For pp being a large prime number, and AFpA \subset \mathbb{F}_p we prove the following: (i)(i) If A(A+A)A(A+A) does not cover all nonzero residues in Fp\mathbb{F}_p, then A<p/8+o(p)|A| < p/8 + o(p). (ii)(ii) If AA is both sum-free and satisfies A=AA = A^*, then A<p/9+o(p)|A| < p/9 + o(p). (iii)(iii) If Aloglogplogpp|A| \gg \frac{\log\log{p}}{\sqrt{\log{p}}}p, then A+A(1o(1))min(2Ap,p)|A + A^*| \geqslant (1 - o(1))\min(2\sqrt{|A|p}, p). Here the constants 1/81/8, 1/91/9, and 22 are the best possible. The proof involves \emph{wrappers}, subsets of a finite abelian group GG, with which we `wrap' popular values in convolutions ABA * B for dense sets A,BGA, B \subseteq G. These objects carry some special structural features, making them capable of addressing both additive-combinatorial and enumerative problems.

Keywords

Cite

@article{arxiv.2011.11468,
  title  = {A new bound for $A(A + A)$ for large sets},
  author = {Aliaksei Semchankau},
  journal= {arXiv preprint arXiv:2011.11468},
  year   = {2023}
}

Comments

13 pages

R2 v1 2026-06-23T20:26:49.829Z