Degree Deviation and Spectral Radius

Fuente: arXiv
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Autores principales: Rautenbach, Dieter, Werner, Florian
Formato: Preprint
Publicado: 2024
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author Rautenbach, Dieter
Werner, Florian
author_facet Rautenbach, Dieter
Werner, Florian
contents For a finite, simple, and undirected graph $G$ with $n$ vertices, $m$ edges, and largest eigenvalue $λ$, Nikiforov introduced the degree deviation of $G$ as $s=\sum_{u\in V(G)}\left|d_G(u)-\frac{2m}{n}\right|$. Contributing to a conjecture of Nikiforov, we show $λ-\frac{2m}{n}\leq \sqrt{\frac{2s}{3}}$. For our result, we show that the largest eigenvalue of a graph that arises from a bipartite graph with $m_{A,B}$ edges by adding $m_A$ edges within one of the two partite sets is at most $\sqrt{m_A+m_{A,B}+\sqrt{m_A^2+2m_Am_{A,B}}}$, which is a common generalization of results due to Stanley and Bhattacharya, Friedland, and Peled.
format Preprint
id arxiv_https___arxiv_org_abs_2409_14956
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Degree Deviation and Spectral Radius
Rautenbach, Dieter
Werner, Florian
Combinatorics
For a finite, simple, and undirected graph $G$ with $n$ vertices, $m$ edges, and largest eigenvalue $λ$, Nikiforov introduced the degree deviation of $G$ as $s=\sum_{u\in V(G)}\left|d_G(u)-\frac{2m}{n}\right|$. Contributing to a conjecture of Nikiforov, we show $λ-\frac{2m}{n}\leq \sqrt{\frac{2s}{3}}$. For our result, we show that the largest eigenvalue of a graph that arises from a bipartite graph with $m_{A,B}$ edges by adding $m_A$ edges within one of the two partite sets is at most $\sqrt{m_A+m_{A,B}+\sqrt{m_A^2+2m_Am_{A,B}}}$, which is a common generalization of results due to Stanley and Bhattacharya, Friedland, and Peled.
title Degree Deviation and Spectral Radius
topic Combinatorics
url https://arxiv.org/abs/2409.14956