A signless Laplacian spectral Erdös-Stone-Simonovits theorem

Fuente: arXiv
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Auteurs principaux: Zheng, Jian, Li, Honghai, Su, Li
Format: Preprint
Publié: 2025
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author Zheng, Jian
Li, Honghai
Su, Li
author_facet Zheng, Jian
Li, Honghai
Su, Li
contents The celebrated Erdős--Stone--Simonovits theorem states that $\mathrm{ex}(n,F)= \big(1-\frac{1}{χ(F)-1}+o(1) \big)\frac{n^{2}}{2}$, where $χ(F)$ is the chromatic number of $F$. In 2009, Nikiforov proved a spectral extension of the Erdős--Stone--Simonovits theorem in terms of the adjacency spectral radius. In this paper, we shall establish a unified extension in terms of the signless Laplacian spectral radius. Let $q(G)$ be the signless Laplacian spectral radius of $G$ and we denote $\mathrm{ex}_{q}(n,F) =\max \{q(G):|G|=n ~\mbox{and}~F\nsubseteq G\}$. It is known that the Erdős--Stone--Simonovits type result for the signless Laplacian spectral radius does not hold for even cycles. We prove that if $F$ is a graph with $χ(F)\geq 3$, then $\mathrm{ex}_{q}(n,F)=\big(1-\frac{1}{χ(F)-1}+o(1) \big)2n$. This solves a problem proposed by Li, Liu and Feng (2022), which gives an entirely satisfactory answer to the problem of estimating $\mathrm{ex}_q(n,F)$. Furthermore, it extends the aforementioned result of Erdős, Stone and Simonovits as well as the spectral result of Nikiforov. Our result indicates that the Erdős--Stone--Simonovits type result regarding the signless Laplacian spectral radius is valid in general.
format Preprint
id arxiv_https___arxiv_org_abs_2502_11170
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A signless Laplacian spectral Erdös-Stone-Simonovits theorem
Zheng, Jian
Li, Honghai
Su, Li
Combinatorics
The celebrated Erdős--Stone--Simonovits theorem states that $\mathrm{ex}(n,F)= \big(1-\frac{1}{χ(F)-1}+o(1) \big)\frac{n^{2}}{2}$, where $χ(F)$ is the chromatic number of $F$. In 2009, Nikiforov proved a spectral extension of the Erdős--Stone--Simonovits theorem in terms of the adjacency spectral radius. In this paper, we shall establish a unified extension in terms of the signless Laplacian spectral radius. Let $q(G)$ be the signless Laplacian spectral radius of $G$ and we denote $\mathrm{ex}_{q}(n,F) =\max \{q(G):|G|=n ~\mbox{and}~F\nsubseteq G\}$. It is known that the Erdős--Stone--Simonovits type result for the signless Laplacian spectral radius does not hold for even cycles. We prove that if $F$ is a graph with $χ(F)\geq 3$, then $\mathrm{ex}_{q}(n,F)=\big(1-\frac{1}{χ(F)-1}+o(1) \big)2n$. This solves a problem proposed by Li, Liu and Feng (2022), which gives an entirely satisfactory answer to the problem of estimating $\mathrm{ex}_q(n,F)$. Furthermore, it extends the aforementioned result of Erdős, Stone and Simonovits as well as the spectral result of Nikiforov. Our result indicates that the Erdős--Stone--Simonovits type result regarding the signless Laplacian spectral radius is valid in general.
title A signless Laplacian spectral Erdös-Stone-Simonovits theorem
topic Combinatorics
url https://arxiv.org/abs/2502.11170