{ "id": "2302.03313", "version": "v1", "published": "2023-02-07T08:26:38.000Z", "updated": "2023-02-07T08:26:38.000Z", "title": "Spectral conditions for forbidden subgraphs in bipartite graphs", "authors": [ "Yuan Ren", "Jing Zhang", "Zhiyuan Zhang" ], "categories": [ "math.CO" ], "abstract": "A graph $G$ is $H$-free, if it contains no $H$ as a subgraph. A graph is said to be \\emph{$H$-minor free}, if it does not contain $H$ as a minor. In recent years, Nikiforov asked that what is the maximum spectral radius of an $H$-free graph of order $n$? In this paper, we consider about some Brualdi-Solheid-Tur\\'{a}n type problems on bipartite graphs. In 2015, Zhai, Lin and Gong proved that if $G$ is a bipartite graph with order $n \\geq 2k+2$ and $\\rho(G)\\geq \\rho(K_{k,n-k})$, then $G$ contains a $C_{2k+2}$ unless $G \\cong K_{k,n-k}$ [Linear Algebra Appl. 471 (2015)]. Firstly, we give a new and more simple proof for the above theorem. Secondly, we prove that if $G$ is a bipartite graph with order $n \\geq 2k+2$ and $\\rho(G)\\geq \\rho(K_{k,n-k})$, then $G$ contains all $T_{2k+3}$ unless $G \\cong K_{k,n-k}$. Finally, we prove that among all outerplanar bipartite graphs on $n>344569$ vertices, $K_{1,n-1}$ attains the maximum spectral radius.", "revisions": [ { "version": "v1", "updated": "2023-02-07T08:26:38.000Z" } ], "analyses": { "keywords": [ "forbidden subgraphs", "spectral conditions", "maximum spectral radius", "linear algebra appl", "outerplanar bipartite graphs" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }