English

Incidences and pairs of dot products

Combinatorics 2015-09-08 v2

Abstract

Let F\mathbb{F} be a field, let PFdP \subseteq \mathbb{F}^d be a finite set of points, and let α,βF{0}\alpha,\beta \in \mathbb{F} \setminus \{0\}. We study the quantity Πα,β={(p,q,r)P×P×Ppq=α,pr=β}.|\Pi_{\alpha, \beta}| = \{(p,q,r) \in P \times P \times P \mid p \cdot q = \alpha, p \cdot r = \beta \}. We observe a connection between the question of placing an upper bound on Πα,β|\Pi_{\alpha,\beta}| and a well-studied question on the number of incidences betwen points and hyperplanes, and use this connection to prove new and strengthened upper bounds on Πα,β|\Pi_{\alpha,\beta}| in a variety of settings.

Keywords

Cite

@article{arxiv.1509.01072,
  title  = {Incidences and pairs of dot products},
  author = {Ben Lund},
  journal= {arXiv preprint arXiv:1509.01072},
  year   = {2015}
}

Comments

9 pages; This version corrects mistakes in Theorems 2 and 7 from the previous version