A characterization of the top trading cycles mechanism for the school choice problem

This paper characterizes the Top Trading Cycles (TTC) mechanism for the school choice problem where schools may have multiple available seats to be assigned to students. We first define weaker forms of fairness, consistency, and resource monotonicity. We show that the TTC mechanism is the unique Pareto efficient and strategy-proof mechanism that satisfies these weaker forms of fairness, consistency and resource monotonicity. We also show that in a well-defined sense TTC is the “most stable” Pareto efficient mechanism.