Maximizing the spectral radius of graphs of given size with forbidden a subgraph

Fuente: arXiv
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Autori principali: Zhang, Yanting, Wang, Ligong
Natura: Preprint
Pubblicazione: 2024
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author Zhang, Yanting
Wang, Ligong
author_facet Zhang, Yanting
Wang, Ligong
contents Let $H_7$ denote the $7$-vertex \textit{fan graph} consisting of a $6$-vertex path plus a vertex adjacent to each vertex of the path. Let $K_3 \vee \frac{m-3}{3}K_1$ be the graph obtained by joining each vertex of a triangle $K_3$ to $\frac{m-3}{3}$ isolated vertices. In this paper, we show that if $G$ is an $H_{7}$-free graph with size $m\geq 33$, then the spectral radius $ ρ(G)\leq 1+\sqrt{m-2},$ equality holds if and only if $G\cong K_3 \vee \frac{m-3}{3}K_1$ (possibly, with some isolated vertices).
format Preprint
id arxiv_https___arxiv_org_abs_2404_06843
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Maximizing the spectral radius of graphs of given size with forbidden a subgraph
Zhang, Yanting
Wang, Ligong
Combinatorics
Let $H_7$ denote the $7$-vertex \textit{fan graph} consisting of a $6$-vertex path plus a vertex adjacent to each vertex of the path. Let $K_3 \vee \frac{m-3}{3}K_1$ be the graph obtained by joining each vertex of a triangle $K_3$ to $\frac{m-3}{3}$ isolated vertices. In this paper, we show that if $G$ is an $H_{7}$-free graph with size $m\geq 33$, then the spectral radius $ ρ(G)\leq 1+\sqrt{m-2},$ equality holds if and only if $G\cong K_3 \vee \frac{m-3}{3}K_1$ (possibly, with some isolated vertices).
title Maximizing the spectral radius of graphs of given size with forbidden a subgraph
topic Combinatorics
url https://arxiv.org/abs/2404.06843