t, and/or have recently been at a particular
                    place.</p>
                <p> If a user's domain is composed of a heterogeneous set of objects (vertices) that can be related to
                    one another in a multitude of ways (edges), then a graph may be the right representation to use. In
                    a graph, each vertex is seen as an atomic entity (not simply a "row in a table") that can be linked
                    to any other vertex or have properties added or removed a