English

Amending the Lonely Runner Spectrum Conjecture

Number Theory 2026-05-06 v2 Combinatorics

Abstract

Let x||x|| be the absolute distance from xx to the nearest integer. For a set of distinct positive integral speeds v1,,vnv_1, \ldots, v_n, we define its maximum loneliness, also known as the gap δ\delta, to be ML(v1,,vn)=maxtRmin1intvi.ML(v_1,\ldots,v_n) = \max_{t \in \mathbb{R}}\min_{1 \leq i \leq n} || tv_i||. The Loneliness Spectrum Conjecture, recently proposed by Kravitz (2021), asserts that sN,ML(v1,,vn)=ssn+1 or ML(v1,,vn)1n.\exists s \in \mathbb{N}, \text{ML}(v_1,\ldots,v_n) = \frac{s} {sn + 1} \text{ or } \text{ML}(v_1,\ldots,v_n) \geq \frac{1}{n}. We disprove the Loneliness Spectrum Conjecture for n=4n = 4 with an infinite family of counterexamples and propose an alternative conjecture. We confirm the amended conjecture for n=4n = 4 whenever there exists a pair of speeds with a common factor of at least 33 and also prove some related results.

Keywords

Cite

@article{arxiv.2306.10417,
  title  = {Amending the Lonely Runner Spectrum Conjecture},
  author = {Ho Tin Fan and Alec Sun},
  journal= {arXiv preprint arXiv:2306.10417},
  year   = {2026}
}

Comments

23 pages

R2 v1 2026-06-28T11:08:01.777Z