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Main Author: Currie, James D.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.09387
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author Currie, James D.
author_facet Currie, James D.
contents Word ${\mathbf G}$ is the fixed point of the morphism $γ=[01,2,02]$. In 2019, Shallit and Shur showed that ${\mathbf G}$ has factor complexity $2n+1$. They also showed that ${\mathbf G}$ has critical exponent $μ=2+\frac{1}{λ^2-1}= 2.4808726\cdots$, where $λ=1.7548777$ is the real zero of $x^3-2x+x-1=0$. They conjectured that this was the least possible critical exponent among words with factor complexity $2n+1$. We confirm their conjecture. The proof, using an intricate case analysis, is by computer. The relevant program generates a `human readable' proof.
format Preprint
id arxiv_https___arxiv_org_abs_2507_09387
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Words with factor complexity $2n+1$ and minimal critical exponent
Currie, James D.
Combinatorics
Formal Languages and Automata Theory
68R15
G.2.1
Word ${\mathbf G}$ is the fixed point of the morphism $γ=[01,2,02]$. In 2019, Shallit and Shur showed that ${\mathbf G}$ has factor complexity $2n+1$. They also showed that ${\mathbf G}$ has critical exponent $μ=2+\frac{1}{λ^2-1}= 2.4808726\cdots$, where $λ=1.7548777$ is the real zero of $x^3-2x+x-1=0$. They conjectured that this was the least possible critical exponent among words with factor complexity $2n+1$. We confirm their conjecture. The proof, using an intricate case analysis, is by computer. The relevant program generates a `human readable' proof.
title Words with factor complexity $2n+1$ and minimal critical exponent
topic Combinatorics
Formal Languages and Automata Theory
68R15
G.2.1
url https://arxiv.org/abs/2507.09387