# Largest eigenvalues of sparse inhomogeneous Erd\H{o}s-R\'enyi graphs

Abstract : We consider inhomogeneous Erd\H{o}s-R\'enyi graphs. We suppose that the maximal mean degree $d$ satisfies $d \ll \log n$. We characterize the asymptotic behavior of the $n^{1 - o(1)}$ largest eigenvalues of the adjacency matrix and its centred version. We prove that these extreme eigenvalues are governed at first order by the largest degrees and, for the adjacency matrix, by the nonzero eigenvalues of the expectation matrix. Our results show that the extreme eigenvalues exhibit a novel behaviour which in particular rules out their convergence to a nondegenerate point process. Together with the companion paper [3], where we analyse the extreme eigenvalues in the complementary regime $d \gg \log n$, this establishes a crossover in the behaviour of the extreme eigenvalues around $d \sim \log n$. Our proof relies on a new tail estimate for the Poisson approximation of an inhomogeneous sum of independent Bernoulli random variables, as well as on an estimate on the operator norm of a pruned graph due to Le, Levina, and Vershynin.
Type de document :
Pré-publication, Document de travail
MAP5 2017-17. 2017
Domaine :

https://hal.archives-ouvertes.fr/hal-01528790
Contributeur : Florent Benaych-Georges <>
Soumis le : lundi 29 mai 2017 - 16:59:20
Dernière modification le : mardi 10 octobre 2017 - 11:22:05

### Identifiants

• HAL Id : hal-01528790, version 1
• ARXIV : 1704.02953

### Citation

Florent Benaych-Georges, Charles Bordenave, Antti Knowles. Largest eigenvalues of sparse inhomogeneous Erd\H{o}s-R\'enyi graphs. MAP5 2017-17. 2017. 〈hal-01528790〉

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