English

On conjectures and problems of Ruzsa concerning difference graphs of S-units

Number Theory 2014-09-09 v1

Abstract

Given a finite nonempty set of primes S, we build a graph G\mathcal{G} with vertex set Q\mathbb{Q} by connecting x and y if the prime divisors of both the numerator and denominator of x-y are from S. In this paper we resolve two conjectures posed by Ruzsa concerning the possible sizes of induced nondegenerate cycles of G\mathcal{G}, and also a problem of Ruzsa concerning the existence of subgraphs of G\mathcal{G} which are not induced subgraphs.

Keywords

Cite

@article{arxiv.1409.2218,
  title  = {On conjectures and problems of Ruzsa concerning difference graphs of S-units},
  author = {Ante Custic and Lajos Hajdu and Dijana Kreso and Robert Tijdeman},
  journal= {arXiv preprint arXiv:1409.2218},
  year   = {2014}
}

Comments

15 pages