The maximum spectral radius of $θ_{2,2,3}$-free graphs with given size

Fuente: arXiv
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Autori principali: Gao, Jing, Li, Xueliang
Natura: Preprint
Pubblicazione: 2025
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author Gao, Jing
Li, Xueliang
author_facet Gao, Jing
Li, Xueliang
contents A theta graph $θ_{r,p,q}$ is the graph obtained by connecting two distinct vertices with three internally disjoint paths of length $r,p,q$, where $q\geq p\geq r\geq1$ and $p\geq2$. A graph is $θ_{r,p,q}$-free if it does not contain $θ_{r,p,q}$ as a subgraph. The maximum spectral radius of $θ_{1,p,q}$-free graphs with given size has been determined for any $q\geq p\geq2$. Zhai, Lin and Shu [Spectral extrema of graphs with fixed size: cycles and complete bipartite graphs, European J. Combin. 95 (2021) 103322] characterized the extremal graph with the maximum spectral radius of $θ_{2,2,2}$-free graphs having $m$ edges. In this paper, we consider the maximum spectral radius of $θ_{2,2,3}$-free graphs with size $m$ and characterize the extremal graph.
format Preprint
id arxiv_https___arxiv_org_abs_2503_19489
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The maximum spectral radius of $θ_{2,2,3}$-free graphs with given size
Gao, Jing
Li, Xueliang
Combinatorics
05C35, 05C50
A theta graph $θ_{r,p,q}$ is the graph obtained by connecting two distinct vertices with three internally disjoint paths of length $r,p,q$, where $q\geq p\geq r\geq1$ and $p\geq2$. A graph is $θ_{r,p,q}$-free if it does not contain $θ_{r,p,q}$ as a subgraph. The maximum spectral radius of $θ_{1,p,q}$-free graphs with given size has been determined for any $q\geq p\geq2$. Zhai, Lin and Shu [Spectral extrema of graphs with fixed size: cycles and complete bipartite graphs, European J. Combin. 95 (2021) 103322] characterized the extremal graph with the maximum spectral radius of $θ_{2,2,2}$-free graphs having $m$ edges. In this paper, we consider the maximum spectral radius of $θ_{2,2,3}$-free graphs with size $m$ and characterize the extremal graph.
title The maximum spectral radius of $θ_{2,2,3}$-free graphs with given size
topic Combinatorics
05C35, 05C50
url https://arxiv.org/abs/2503.19489