English

On the sizes of large subgraphs of the binomial random graph

Combinatorics 2021-09-23 v2

Abstract

We consider the binomial random graph G(n,p)G(n,p), where pp is a constant, and answer the following two questions. First, given e(k)=p(k2)+O(k)e(k)=p{k\choose 2}+O(k), what is the maximum kk such that a.a.s.~the binomial random graph G(n,p)G(n,p) has an induced subgraph with kk vertices and e(k)e(k) edges? We prove that this maximum is not concentrated in any finite set (in contrast to the case of a small e(k)e(k)). Moreover, for every constant C>0C>0 and every ωn\omega_n\to\infty, a.a.s.~the size of the concentration set belongs to (Cn/lnn,ωnn/lnn)(C\sqrt{n/\ln n},\omega_n\sqrt{n/\ln n}). Second, given k>εnk>\varepsilon n, what is the maximum μ\mu such that a.a.s.~the set of sizes of kk-vertex subgraphs of G(n,p)G(n,p) contains a full interval of length μ\mu? The answer is μ=Θ((nk)nln(nk))\mu=\Theta\left(\sqrt{(n-k)n\ln{n\choose k}}\right).

Keywords

Cite

@article{arxiv.1904.05307,
  title  = {On the sizes of large subgraphs of the binomial random graph},
  author = {Jozsef Balogh and Maksim Zhukovskii},
  journal= {arXiv preprint arXiv:1904.05307},
  year   = {2021}
}