# Bootstrap percolation in three dimensions

## Abstract

By bootstrap percolation we mean the following deterministic process on a graph G. Given a set A of vertices "infected" at time 0, new vertices are subsequently infected, at each time step, if they have at least r ∈ N previously infected neighbors. When the set A is chosen at random, the main aim is to determine the critical probability pc(G, r) at which percolation (infection of the entire graph) becomes likely to occur. This bootstrap process has been extensively studied on the d-dimensional grid [n]d: with 2 ≤ r ≤ d fixed, it was proved by Cerf and Cirillo (for d = r = 3), and by Cerf and Manzo (in general), that where log(r) is an r-times iterated logarithm. However, the exact threshold function is only known in the case d = r = 2, where it was shown by Holroyd to be. In this paper we shall determine the exact threshold in the crucial case d = r = 3, and lay the groundwork for solving the problem for all fixed d and r. © Institute of Mathematical Statistics, 2009.

## Publication Title

Annals of Probability

## Recommended Citation

Balogh, J., Bollobás, B., & Morris, R.
(2009). Bootstrap percolation in three dimensions.* Annals of Probability**, 37* (4), 1329-1380.
https://doi.org/10.1214/08-AOP433