English

On the time for a runner to get lonely

Combinatorics 2022-02-17 v2

Abstract

The Lonely Runner Conjecture asserts that if nn runners with distinct constant speeds run on the unit circle R/Z\mathbb{R}/\mathbb{Z} starting from 00 at time 00, then each runner will at some time t>0t>0 be lonely in the sense that she/he will be separated by a distance at least 1/n1/n from all the others at time tt. In investigating the size of tt, we show that an upper bound for tt in terms of a certain number of rounds (which, in the case where the lonely runner is static, corresponds to the number of rounds of the slowest non-static runner) is equivalent to a covering problem in dimension n2n-2. We formulate a conjecture regarding this covering problem and prove it to be true for n=3,4,5,6n=3,4,5,6. Then, we use our method of proof to demonstrate that the Lonely Runner Conjecture with Free Starting Positions is satisfied for n=3,4n=3,4. Finally, we show that the so-called gap of loneliness in one round (with respect to the Lonely Runner Conjecture), where we have m+1m+1 runners including one static runner, is bounded from below by 1/(2m1)1/(2m-1) for all integer m2m\geq 2.

Keywords

Cite

@article{arxiv.2111.13688,
  title  = {On the time for a runner to get lonely},
  author = {Ludovic Rifford},
  journal= {arXiv preprint arXiv:2111.13688},
  year   = {2022}
}

Comments

59 pages, 14 figures

R2 v1 2026-06-24T07:53:32.352Z