Title
On the maximum running time in graph bootstrap percolation
Abstract
Graph bootstrap percolation is a simple cellular automaton introduced by Bollobas in 1968. Given a graph H and a set G subset of E(K-n) we initially 'infect' all edges in G and then, in consecutive steps, we infect every e is an element of K-n that completes a new infected copy of H in K-n. We say that G percolates if eventually every edge in K-n is infected. The extremal question about the size of the smallest percolating sets when H = K-r was answered independently by Alon, Kalai and Frankl. Here we consider a different question raised more recently by Bollobas: what is the maximum time the process can run before it stabilizes? It is an easy observation that for r = 3 this maximum is [log(2)(n - 1)]. However, a new phenomenon occurs for r = 4 when, as we show, the maximum time of the process is n - 3. For r >= 5 the behaviour of the dynamics is even more complex, which we demonstrate by showing that the K-r-bootstrap process can run for at least n(2-epsilon r) time steps for some epsilon(r) that tends to 0 as r -> infinity.
Year
Venue
Keywords
2017
ELECTRONIC JOURNAL OF COMBINATORICS
Bootstrap percolation,weak saturation,cellular automata,monotone cellular automata,extremal combinatorics
Field
DocType
Volume
Cellular automaton,Discrete mathematics,Graph,Combinatorics,Bootstrap percolation,Mathematics
Journal
24.0
Issue
ISSN
Citations 
2.0
1077-8926
1
PageRank 
References 
Authors
0.63
7
4
Name
Order
Citations
PageRank
Bela Bollobas16612.05
Michal Przykucki2356.79
Oliver Riordan328538.31
J. Sahasrabudhe432.79