abstract:
Bootstrap percolation is one of the simplest cellular automata. One
of its basic variants is bootstrap percolation on a grid \([n]^d\) or lattice \(\mathbb{Z}^d\) with infection parameter r. This starts with a set \(A_0\) of initially infected sites (vertices); at each time step \(t = 1, 2, \ldots \) every site with at least \(r\) infected neighbours becomes infected. An infected site remain infected forever. We say that \(A_0\) percolates (with parameter \(r\)) if eventually all sites get infected; the time of percolation is the minimal \(t\) with \(A_t = V (G)\), and the speed of percolation is the number of vertices divided by this time.
In the talk I shall present a number of fundamental extremal and
probabilistic results on bootstrap percolation, including the fundamen-
tal results due to Aizenman, Lebowitz, Schonman, Holroyd, Benevides,
Przykucki, and others, and some of the results I have proved recently
with Balogh, Morris, Duminil-Copin, Riordan, Holmgren, Smith and
Uzzell.