Robustness of equilibrium price dispersion in finite market games

We propose an approach to restricting the set of equilibria in a market game and use\ud it to assess the robustness of the price dispersion results obtained by Koutsougeras\ud [2003, J. Econ. Theory 108, 169–175] in the multiple trading posts setup. More\ud precisely, we perturb the initial game by the introduction of transaction costs and\ud our main results are the following. (i) No equilibrium with price dispersion of\ud the game with costless transactions can be approached by equilibria with positive\ud transaction costs as costs get arbitrarily small. (ii) When this type of perturbation\ud is considered the set of equilibrium outcomes is not affected by the number of\ud trading posts. In addition, the analysis hints at conditions required for non-zero\ud transaction costs to serve as a source of price dispersion in this class of exchange\ud economies