English

Product-free sets in the free group

Combinatorics 2024-09-12 v2

Abstract

We prove that product-free sets of the free group over a finite alphabet have maximum density 1/21/2 with respect to the natural measure that assigns total weight one to each set of irreducible words of a given size. This confirms a conjecture of Leader, Letzter, Narayanan and Walters. In more general terms, we actually prove that strongly kk-product-free sets have maximum density 1/k1/k in terms of the said measure.

Keywords

Cite

@article{arxiv.2302.03748,
  title  = {Product-free sets in the free group},
  author = {Miquel Ortega and Juanjo Rué and Oriol Serra},
  journal= {arXiv preprint arXiv:2302.03748},
  year   = {2024}
}

Comments

10 pages. Uploaded accepted version including some changes suggested by anonymous referees

R2 v1 2026-06-28T08:34:35.519Z