FIG. 1.

Initial propagation model. The top part depicts a spatial representation of the system, composed of two 1×1 boxes separated by an impermeable border (vertical dashed line). Also represented are the amplitude of the random walk of a person (blue), the bounce when encountering the external boundaries (green), and the radius of the infection (red); note that, for the sake of clarity, these magnitudes are not represented at scale. The bottom part depicts the compartments and transition probabilities of the SIR model.