Figure 11.

The Bai Model [26,34,35] with 5 variables (SEIRD): the number of susceptible S, exposed E, infected I, recovered R, and dead D individuals. This model has a similar structure in terms of organizations to the Nesteruk model: there is no organization containing species representing the infection. Thus infection is implicitly assumed to vanish in the long-term. The remaining multitude of organizations exists simply due to the fact that recovered individuals R and dead individuals D can be combined arbitrarily with each other and with susceptible individuals S to form organizations. The signature of this model is: $\varnothing ,\underset{\_}{\text{X}}$.