English

The binomial random graph is a bad inducer

Combinatorics 2024-08-26 v2

Abstract

For a finite graph FF and a value p[0,1]p \in [0,1], let I(F,p)I(F,p) denote the largest yy for which there is a sequence of graphs of edge density approaching pp so that the induced FF-density of the sequence approaches yy. We show that for all FF on at least three vertices and all p(0,1)p \in (0,1), the binomial random graph G(n,p)G(n,p) has induced FF-density strictly less than I(F,p).I(F,p). This provides a negative answer to a problem posed by Liu, Mubayi and Reiher. Our approach is in the limiting setting of graphons, and we in fact show a stronger result: the binomial random graph is never a \emph{local} maximum in the space of graphons of edge density pp. This is done by finding a sequence of balanced perturbations of arbitrarily small norm that increase the FF-density.

Keywords

Cite

@article{arxiv.2306.13014,
  title  = {The binomial random graph is a bad inducer},
  author = {Vishesh Jain and Marcus Michelen and Fan Wei},
  journal= {arXiv preprint arXiv:2306.13014},
  year   = {2024}
}

Comments

13 pages. Significantly new results and proof. Fan Wei added as an author. VJ and MM thank an anonymous referee for pointing out an error in a proof in v1

R2 v1 2026-06-28T11:12:07.140Z