  Written to be contributed as the "mathematical modeling" chapter of a book,
edited by Elaine Landry, to be titled "Categories for the Working Philosopher".
In this chapter, category theory is presented as a mathematical modeling
framework that highlights the relationships between objects, rather than the
objects in themselves. A working definition of model is given, and several
examples of mathematical objects, such as vector spaces, groups, and dynamical
systems, are considered as categorical models.
