Propagation of fronts in cellular automata

The problem of propagation of fronts (traveling fronts) is investigated for two classes of two-dimensional cellular automata: simple totalistic automata with states 0,1, and Greenberg-Hastings automata that minic infection processes. These automata are investigated with analytic and with simulation methods. In the deterministic case the exact shapes of (anisotropic) fronts are determined as well as the propagation speed in several directions. In the stochastic case the fronts are investigated by simulation.