Boundary rules and breaking of self-organized criticality in 2D frozen percolation

TL;DR

This paper investigates how boundary conditions influence the behavior of frozen percolation on a 2D triangular lattice, revealing significant effects in diameter-based freezing and discussing implications for volume-based freezing.

Contribution

It demonstrates that boundary conditions significantly impact diameter-frozen percolation behavior, contrasting with previous models where boundaries remained vacant forever.

Findings

Boundary conditions strongly affect diameter-frozen percolation.

Differences between diameter and volume freezing behaviors are highlighted.

The influence of boundary rules is less clear in volume freezing, discussed briefly.

Abstract

We study frozen percolation on the (planar) triangular lattice, where connected components stop growing ("freeze") as soon as their "size" becomes at least $N$, for some parameter $N \geq 1$. The size of a connected component can be measured in several natural ways, and we consider the two particular cases of diameter and volume (i.e. number of sites). Diameter-frozen and volume-frozen percolation have been studied in previous works, and they display radically different behaviors. These works adopt the rule that the boundary of a frozen cluster stays vacant forever, and we investigate the influence of these "boundary conditions" in the present paper. We prove the (somewhat surprising) result that they strongly matter in the diameter case, and we discuss briefly the volume case.