Figure 4. The conversion rules (i) and (ii) are illustrated.

In each case the black disc represents an agent whose prospects for conversion are being assessed. Red discs correspond to active agents and blue discs to passive agents. White discs correspond to agents whose status (active or passive) is irrelevant. In rule (i), the black active agent has a probability of converting, independent of the status of its neighbors. In rule (ii), the agent has probability 0 of converting if all of the eight agents in its Moore neighborhood (that is, the four nearest and four next nearest-neighbor sites) are active, while it has probability of converting if at least one of the eight agents in its Moore neighborhood is passive.