Unit II Advanced Structural Modeling A relationship is a connection among things. In object-oriented modeling, the four most important relationships are dependencies, generalizations, associations, and realizations. Graphically, a relationship is rendered as a path, with different kinds of lines used to distinguish the different relationships. Dependency A dependency is a using relationship, specifying that a change in the specification of one thing may affect another thing that uses it, but not necessarily the reverse. Graphically, a dependenc...