English

Climbing up a random subgraph of the hypercube

Combinatorics 2023-12-12 v2 Probability

Abstract

Let QdQ^d be the dd-dimensional binary hypercube. We say that P={v1,,vk}P=\{v_1,\ldots, v_k\} is an increasing path of length k1k-1 in QdQ^d, if for every i[k1]i\in [k-1] the edge vivi+1v_iv_{i+1} is obtained by switching some zero coordinate in viv_i to a one coordinate in vi+1v_{i+1}. Form a random subgraph QpdQ^d_p by retaining each edge in E(Qd)E(Q^d) independently with probability pp. We show that there is a phase transition with respect to the length of a longest increasing path around p=edp=\frac{e}{d}. Let α\alpha be a constant and let p=αdp=\frac{\alpha}{d}. When α<e\alpha<e, then there exists a δ[0,1)\delta \in [0,1) such that whp a longest increasing path in QpdQ^d_p is of length at most δd\delta d. On the other hand, when α>e\alpha>e, whp there is a path of length d2d-2 in QpdQ^d_p, and in fact, whether it is of length d2,d1d-2, d-1, or dd depends on whether the all-zero and all-one vertices percolate or not.

Keywords

Cite

@article{arxiv.2311.16631,
  title  = {Climbing up a random subgraph of the hypercube},
  author = {Michael Anastos and Sahar Diskin and Dor Elboim and Michael Krivelevich},
  journal= {arXiv preprint arXiv:2311.16631},
  year   = {2023}
}
R2 v1 2026-06-28T13:33:53.916Z