Asymptotic Tightness of the Pigeonhole Bound for Large-Order Davenport-Schinzel Sequences

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Autor principal: Geneson, Jesse
Formato: Preprint
Publicado: 2026
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author Geneson, Jesse
author_facet Geneson, Jesse
contents We prove that the pigeonhole upper bound $λ(s,m) \leq \binom{m}{2}(s+1)$ is asymptotically tight whenever $s/\!\sqrt{m} \to \infty$. In particular, $λ(s,m) \sim \binom{m}{2}\,s$ in this regime. As corollaries: $λ(n,n)/n^3 \to \frac{1}{2}$, resolving the leading constant from the previously known interval $[\frac{1}{3}, \frac{1}{2}]$; and more generally $λ(an,bn) \sim \frac{ab^2}{2}\,n^3$ for any constants $a,b > 0$.
format Preprint
id arxiv_https___arxiv_org_abs_2602_15375
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Asymptotic Tightness of the Pigeonhole Bound for Large-Order Davenport-Schinzel Sequences
Geneson, Jesse
Combinatorics
Discrete Mathematics
We prove that the pigeonhole upper bound $λ(s,m) \leq \binom{m}{2}(s+1)$ is asymptotically tight whenever $s/\!\sqrt{m} \to \infty$. In particular, $λ(s,m) \sim \binom{m}{2}\,s$ in this regime. As corollaries: $λ(n,n)/n^3 \to \frac{1}{2}$, resolving the leading constant from the previously known interval $[\frac{1}{3}, \frac{1}{2}]$; and more generally $λ(an,bn) \sim \frac{ab^2}{2}\,n^3$ for any constants $a,b > 0$.
title Asymptotic Tightness of the Pigeonhole Bound for Large-Order Davenport-Schinzel Sequences
topic Combinatorics
Discrete Mathematics
url https://arxiv.org/abs/2602.15375