Fig. 1

Model schematic of co-contagion diffusion. All nodes have a one-to-one correspondence to themselves between layers. At time step 1 (left), assume the blue node is infected with both Contagions A and B. Contagion A only diffuses on the top lattice layer, and Contagion B diffuses on the bottom power-law layer. Yellow nodes denote nodes that are susceptible to infection, whose adaption probability depends on neighbors who are infected (blue over total neighbors). Assuming all susceptible nodes adopt respective contagions this round, the right diagram shows adoption of A and B by time step 2. Contagion B has now infected a hub with five neighbors, shown in yellow. Individual P will decide whether to adapt A and B, based on the denisties of both A and B from both layers. When dormancy is considered, blue nodes are excluded from the numerator as illustrated in Eq. 2