Equilibrium, Auction, Multiple Substitutes and Complements

We study a market model where there are n different types of indivisible goods for sale. The goods can be substitutable or complementary. There are multiple units of each good. Each agent may consume several goods and has quasi-linear utilities in money. We introduce a general condition which will be shown to guarantee the existence of a Walrasian equilibrium and generalize several existing conditions such as gross substitutes, strong substitutes, and gross substitutes and complements. We also identify several characterizations of this condition. Furthermore, we propose a price adjustment process which converges globally to a Walrasian equilibrium.