English

On the quotient set of the distance set

Classical Analysis and ODEs 2019-05-29 v1 Combinatorics Number Theory

Abstract

Let Fq{\Bbb F}_q be a finite field of order q.q. We prove that if d2d\ge 2 is even and EFqdE \subset {\Bbb F}_q^d with E9qd2|E| \ge 9q^{\frac{d}{2}} then Fq=Δ(E)Δ(E)={ab:aΔ(E),bΔ(E)\{0}}, {\Bbb F}_q=\frac{\Delta(E)}{\Delta(E)}=\left\{ \frac{a}{b}: a \in \Delta(E), b \in \Delta(E) \backslash \{0\} \right\}, where Δ(E)={xy:x,yE}, x=x12+x22++xd2. \Delta(E)=\{||x-y||: x,y \in E\}, \ ||x||=x_1^2+x_2^2+\cdots+x_d^2. If the dimension dd is odd and EFqdE\subset \mathbb F_q^d with E6qd2,|E|\ge 6q^{\frac{d}{2}}, then {0}Fq+Δ(E)Δ(E), \{0\}\cup\mathbb F_q^+ \subset \frac{\Delta(E)}{\Delta(E)}, where Fq+\mathbb F_q^+ denotes the set of nonzero quadratic residues in Fq.\mathbb F_q. Both results are, in general, best possible, including the conclusion about the nonzero quadratic residues in odd dimensions.

Keywords

Cite

@article{arxiv.1802.08297,
  title  = {On the quotient set of the distance set},
  author = {A. Iosevich and D. Koh and H. Parshall},
  journal= {arXiv preprint arXiv:1802.08297},
  year   = {2019}
}