Title
Monotone Cellular Automata in a Random Environment.
Abstract
In this paper we study in complete generality the family of two-state, deterministic, monotone, local, homogeneous cellular automata in Z(d) with random initial configurations. Formally, we are given a set U = {X-1,...,X-m} of finite subsets of Z(d) \ {0}, and an initial set A(0) subset of Z(d) of 'infected' sites, which we take to be random according to the product measure with density p. At time t is an element of N, the set of infected sites A(t) is the union of A(t-1) and the set of all x is an element of Z(d) such that x + X is an element of A(t-1) for some X is an element of U. Our model may alternatively be thought of as bootstrap percolation on Z(d) with arbitrary update rules, and for this reason we call it U-bootstrap percolation. In two dimensions, we give a classification of U-bootstrap percolation models into three classes -supercritical, critical and subcritical - and we prove results about the phase transitions of all models belonging to the first two of these classes. More precisely, we show that the critical probability for percolation on (Z/nZ)(2) is (log n)(-Theta(1)) for all models in the critical class, and that it is n(-Theta(1)) for all models in the supercritical class. The results in this paper are the first of any kind on bootstrap percolation considered in this level of generality, and in particular they are the first that make no assumptions of symmetry. It is the hope of the authors that this work will initiate a new, unified theory of bootstrap percolation on Z(d).
Year
DOI
Venue
2015
10.1017/S0963548315000012
COMBINATORICS PROBABILITY & COMPUTING
Keywords
Field
DocType
mathematics
Discrete mathematics,Binary logarithm,Cellular automaton,Combinatorics,Product measure,Phase transition,Unified field theory,Continuum percolation theory,Percolation,Mathematics,Monotone polygon
Journal
Volume
Issue
ISSN
24
SP4
0963-5483
Citations 
PageRank 
References 
5
1.05
2
Authors
3
Name
Order
Citations
PageRank
Béla Bollobás12696474.16
Paul Smith251.05
Andrew J. Uzzell3134.48