English

Moderate deviations of triangle counts in sparse Erd\H{o}s-R\'enyi random graphs $G(n,m)$ and $G(n,p)$

Combinatorics 2025-01-13 v2 Probability

Abstract

We consider the question of determining the probability of triangle count deviations in the Erd\H{o}s-R\'enyi random graphs G(n,m)G(n,m) and G(n,p)G(n,p) with densities larger than n1/2(logn)1/2n^{-1/2}(\log{n})^{1/2}. In particular, we determine the log probability logP(N(G)>(1+δ)p3n3)\log\mathbb{P}(N_{\triangle}(G)\, >\, (1+\delta)p^3n^3) up to a constant factor across essentially the entire range of possible deviations, in both the G(n,m)G(n,m) and G(n,p)G(n,p) model. For the G(n,p)G(n,p) model we also prove a stronger result, up to a (1+o(1))(1+o(1)) factor, in the non-localised regime. We also obtain some results for the lower tail and for counts of cherries (paths of length 22).

Keywords

Cite

@article{arxiv.2305.04326,
  title  = {Moderate deviations of triangle counts in sparse Erd\H{o}s-R\'enyi random graphs $G(n,m)$ and $G(n,p)$},
  author = {José D. Alvarado and Leonardo Gonçalves de Oliveira and Simon Griffiths},
  journal= {arXiv preprint arXiv:2305.04326},
  year   = {2025}
}