A Polyhedral Study of Integer Variable Upper Bounds

We study the polyhedron of the single node capacitated network design model with integer variable upper bounds. We first give a characterization of valid inequalities that is useful in proving the validity of several classes of inequalities. Next we derive several classes of valid inequalities and we give conditions for them to be facet-defining. Sequence independent lifting is used to obtain additional facets. We conclude by reporting computational results with a branch-and-cut algorithm.