Partial Chebyshev Polynomials and Fan Graphs

Fuente: arXiv
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Auteurs principaux: Młotkowski, Wojciech, Obata, Nobuaki
Format: Preprint
Publié: 2024
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author Młotkowski, Wojciech
Obata, Nobuaki
author_facet Młotkowski, Wojciech
Obata, Nobuaki
contents Motivated by the product formula of the Chebyshev polynomials of the second kind $U_n(x)$, we newly introduce the partial Chebyshev polynomials $U^{\mathrm{e}}_n(x)$ and $U^{\mathrm{o}}_n(x)$ and derive their basic properties, relations to the classical Chebyshev polynomials, and new factorization formulas for $U_n(x)$. In order to calculate the quadratic embedding constant (QEC) of a fan graph $K_1+P_n$, we derive a new polynomial $ϕ_n(x)$ which is factorized by partial Chebyshev polynomial $U^{\mathrm{e}}_n(x)$. We prove that $\mathrm{QEC}(K_1+P_n)$ is given in terms of the minimal zero of $ϕ_n(x)$, and obtain the explicit value of $\mathrm{QEC}(K_1+P_n)$ for an even $n$ and its reasonable exstimate for an odd $n$.
format Preprint
id arxiv_https___arxiv_org_abs_2412_10697
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Partial Chebyshev Polynomials and Fan Graphs
Młotkowski, Wojciech
Obata, Nobuaki
Combinatorics
05C50, 06C76, 51K99, 42C05
Motivated by the product formula of the Chebyshev polynomials of the second kind $U_n(x)$, we newly introduce the partial Chebyshev polynomials $U^{\mathrm{e}}_n(x)$ and $U^{\mathrm{o}}_n(x)$ and derive their basic properties, relations to the classical Chebyshev polynomials, and new factorization formulas for $U_n(x)$. In order to calculate the quadratic embedding constant (QEC) of a fan graph $K_1+P_n$, we derive a new polynomial $ϕ_n(x)$ which is factorized by partial Chebyshev polynomial $U^{\mathrm{e}}_n(x)$. We prove that $\mathrm{QEC}(K_1+P_n)$ is given in terms of the minimal zero of $ϕ_n(x)$, and obtain the explicit value of $\mathrm{QEC}(K_1+P_n)$ for an even $n$ and its reasonable exstimate for an odd $n$.
title Partial Chebyshev Polynomials and Fan Graphs
topic Combinatorics
05C50, 06C76, 51K99, 42C05
url https://arxiv.org/abs/2412.10697