On the Asymptotic Palindrome Density of Fibonacci Infinite Words

Fuente: arXiv
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Main Authors: Abdullah, Duaa, Hamoud, Jasem
Format: Preprint
Published: 2025
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author Abdullah, Duaa
Hamoud, Jasem
author_facet Abdullah, Duaa
Hamoud, Jasem
contents In this paper, we investigate the combinatorial and density properties of infinite words generated by Fibonacci-type morphisms, focusing on their subword structure, palindrome density, and extremal statistical behaviors. Using the morphism $0 \to 01$, $1 \to 0$, we define a derived ternary word $\mathbb{Y}$ and establish new results relating its density components $\mathrm{dens}(λ,n)$, $\mathrm{dens}(α,n)$, and $\mathrm{dens}(β,n)$, deriving explicit formulae and bounds on their behavior. We further prove a general density theorem for infinite words with paired subwords, showing that the associated palindromic prefix density is bounded above by $\frac{1}{φ_1}$, where $φ_1 = (1 + \sqrt{5})/2$ is the golden ratio. Our approach connects the structure of Fibonacci and Thue--Morse sequences with precise asymptotic and combinatorial interpretations for the observed densities.
format Preprint
id arxiv_https___arxiv_org_abs_2511_06485
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Asymptotic Palindrome Density of Fibonacci Infinite Words
Abdullah, Duaa
Hamoud, Jasem
Combinatorics
05C42, 11B05, 11R45, 11B39, 68R15
G.2.0; F.2.2
In this paper, we investigate the combinatorial and density properties of infinite words generated by Fibonacci-type morphisms, focusing on their subword structure, palindrome density, and extremal statistical behaviors. Using the morphism $0 \to 01$, $1 \to 0$, we define a derived ternary word $\mathbb{Y}$ and establish new results relating its density components $\mathrm{dens}(λ,n)$, $\mathrm{dens}(α,n)$, and $\mathrm{dens}(β,n)$, deriving explicit formulae and bounds on their behavior. We further prove a general density theorem for infinite words with paired subwords, showing that the associated palindromic prefix density is bounded above by $\frac{1}{φ_1}$, where $φ_1 = (1 + \sqrt{5})/2$ is the golden ratio. Our approach connects the structure of Fibonacci and Thue--Morse sequences with precise asymptotic and combinatorial interpretations for the observed densities.
title On the Asymptotic Palindrome Density of Fibonacci Infinite Words
topic Combinatorics
05C42, 11B05, 11R45, 11B39, 68R15
G.2.0; F.2.2
url https://arxiv.org/abs/2511.06485