A spectral Erdős-Rademacher theorem

Fuente: arXiv
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Autores principales: Li, Yongtao, Lu, Lu, Peng, Yuejian
Formato: Preprint
Publicado: 2024
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author Li, Yongtao
Lu, Lu
Peng, Yuejian
author_facet Li, Yongtao
Lu, Lu
Peng, Yuejian
contents A classical result of Erdős and Rademacher (1955) indicates a supersaturation phenomenon. It says that if $G$ is a graph on $n$ vertices with at least $\lfloor {n^2}/{4} \rfloor +1$ edges, then $G$ contains at least $\lfloor {n}/{2}\rfloor$ triangles. We prove a spectral version of Erdős--Rademacher's theorem. Moreover, Mubayi [Adv. Math. 225 (2010)] extends the result of Erdős and Rademacher from a triangle to any color-critical graph. It is interesting to study the extension of Mubayi from a spectral perspective. However, it is not apparent to measure the increment on the spectral radius of a graph comparing to the traditional edge version (Mubayi's result). In this paper, we provide a way to measure the increment on the spectral radius of a graph and propose a spectral version on the counting problems for color-critical graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2406_05609
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A spectral Erdős-Rademacher theorem
Li, Yongtao
Lu, Lu
Peng, Yuejian
Combinatorics
05C50, 05C35
A classical result of Erdős and Rademacher (1955) indicates a supersaturation phenomenon. It says that if $G$ is a graph on $n$ vertices with at least $\lfloor {n^2}/{4} \rfloor +1$ edges, then $G$ contains at least $\lfloor {n}/{2}\rfloor$ triangles. We prove a spectral version of Erdős--Rademacher's theorem. Moreover, Mubayi [Adv. Math. 225 (2010)] extends the result of Erdős and Rademacher from a triangle to any color-critical graph. It is interesting to study the extension of Mubayi from a spectral perspective. However, it is not apparent to measure the increment on the spectral radius of a graph comparing to the traditional edge version (Mubayi's result). In this paper, we provide a way to measure the increment on the spectral radius of a graph and propose a spectral version on the counting problems for color-critical graphs.
title A spectral Erdős-Rademacher theorem
topic Combinatorics
05C50, 05C35
url https://arxiv.org/abs/2406.05609