Abstract
In the bootstrap percolation model, sites in an L×L square are initially infected independently with probability p. At subsequent steps, a healthy site becomes infected if it has at least two infected neighbors. As (L, p)→(∞, 0), the probability that the entire square is eventually infected is known to undergo a phase transition in the parameter p log L, occurring asymptotically at λ=π2/18 [Probab. Theory Related Fields 125 (2003) 195–224]. We prove that the discrepancy between the critical parameter and its limit λ is at least Ω((log L)−1/2). In contrast, the critical window has width only Θ((log L)−1). For the so-called modified model, we prove rigorous explicit bounds which imply, for example, that the relative discrepancy is at least 1% even when L=103000. Our results shed some light on the observed differences between simulations and rigorous asymptotics.
Citation
Janko Gravner. Alexander E. Holroyd. "Slow convergence in bootstrap percolation." Ann. Appl. Probab. 18 (3) 909 - 928, June 2008. https://doi.org/10.1214/07-AAP473
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