PROFESSOR: In Chapter 3, we will study epidemiological models,
which describe the spread of an infection
and then the recovery from that infection in a population.
And the traditional epidemiological models
that we will study for populations,
and also adapt to indoor spaces, involve
keeping track of compartments or subgroups of populations,
such as the number of susceptible people,
the number of infected, exposed, and recovered.
So for example, an infected person
can expose a susceptible, and then
the exposed person can themselves become infected,
or they may eventually recover.
And there are various rates for these different processes.
And this leads to a set of nonlinear differential
equations that describe the evolution and growth, and then
ultimately decay, of an epidemic.