In the epidemic Model (4.83), show by using linearization that the positive equilibrium point x∗ is asymptotically stable if In the epidemic Model (4.83), introduce a third population group that...

In the epidemic Model (4.83), show by using linearization that the positive equilibrium point x∗ is asymptotically stable if

In the epidemic Model (4.83), introduce a third population group that infects members of the group and those outside, and analyze the stability of the model.