Price Variation in a Bipartite Exchange Network

We analyze the variation of prices in a model of an exchange market introduced by Kakade et al. [11], in which buyers and sellers are represented by vertices of a bipartite graph and trade is allowed only between neighbors. In this model the graph is generated probabilistically, and each buyer is connected via preferential attachment to v sellers. We show that even though the tail of the degree distribution of the sellers gets heavier as v increases, the prices at equilibrium decrease exponentially with v. This strengthens the intuition that as the number of vendors available to buyers increases, the prices of goods decrease.