The bunkbed conjecture holds in the $p\uparrow 1$ limit

TL;DR

This paper proves that Kasteleyn's bunkbed conjecture is valid in the high-probability limit (as p approaches 1) for any finite graph, confirming the conjecture in this regime.

Contribution

The authors establish that the bunkbed conjecture holds for all sufficiently large p close to 1 in finite graphs, a significant partial confirmation of the conjecture.

Findings

The conjecture is valid for p near 1 in finite graphs.

Existence of a threshold epsilon(G) for each finite graph G.

The result applies to all finite graphs in the high-percolation probability limit.

Abstract

Let $G=(V,E)$ be a countable graph. The Bunkbed graph of $G$ is the product graph $G \times K_2$, which has vertex set $V\times \{0,1\}$ with "horizontal'' edges inherited from $G$ and additional "vertical'' edges connecting $(w,0)$ and $(w,1)$ for each $w \in V$. Kasteleyn's bunkbed conjecture states that for each $u,v \in V$ and $p\in [0,1]$, the vertex $(u,0)$ is at least as likely to be connected to $(v,0)$ as to $(v,1)$ under Bernoulli-$p$ bond percolation on the bunkbed graph. We prove that the conjecture holds in the $p \uparrow 1$ limit in the sense that for each finite graph $G$ there exists $\varepsilon(G)>0$ such that the bunkbed conjecture holds for $p \geqslant 1-\varepsilon(G)$.