#08-07:

We study the assignment model where a collection of indivisible goods are sold to a set of buyers who want to buy at most one good. We characterize the extreme and interior points of the Walrasian equilibrium price space of this model. Our characteri- zations are in terms of demand sets of buyers. As a corollary to these characterizations, we characterize the minimum and the maximum Walrasian equilibrium price vectors. We also give necessary and sucient conditions under which the interior of the Wal- rasian equilibrium price vector space is non-empty. Some of our results are derived by interpreting the Walrasian equilibrium price vectors as potential functions of an appropriate directed graph.