English

Minimum degree $k$ and $k$-connectedness usually arrive together

Combinatorics 2024-09-25 v2 Probability

Abstract

Let d,nNd,n\in \mathbb{N} be such that d=ω(1)d=\omega(1), and dn1ad\le n^{1-a} for some constant a>0a>0. Consider a dd-regular graph G=(V,E)G=(V, E) and the random graph process that starts with the empty graph G(0)G(0) and at each step G(i)G(i) is obtained from G(i1)G(i-1) by adding uniformly at random a new edge from EE. We show that if GG satisfies some (very) mild global edge-expansion, and an almost optimal edge-expansion of sets up to order O(dlogn)O(d\log n), then for any constant kNk\in \mathbb{N} in the random graph process on GG, typically the hitting times of minimum degree at least kk and of kk-connectedness are equal. This, in particular, covers both dd-regular high dimensional product graphs and pseudo-random graphs, and confirms a conjecture of Joos from 2015. We further demonstrate that this result is tight in the sense that there are dd-regular nn-vertex graphs with optimal edge-expansion of sets up to order Ω(d)\Omega(d), for which the probability threshold of minimum degree at least one is different than the probability threshold of connectivity.

Keywords

Cite

@article{arxiv.2409.14398,
  title  = {Minimum degree $k$ and $k$-connectedness usually arrive together},
  author = {Sahar Diskin and Anna Geisler},
  journal= {arXiv preprint arXiv:2409.14398},
  year   = {2024}
}

Comments

11 pages

R2 v1 2026-06-28T18:52:48.355Z