An incompatibility between recursive unanimity and strategy-proofness in two-sided matching problems

In this article, we study the incompatibilities for the properties on matching rules in two-sided many-to-one matching problems under responsive preferences. We define a new property called respect for recursive unanimity. This property requires that if every agent matches with its first choice among its really possible choices that are based on a recursive procedure like the well-known top trading cycles algorithm, then we should respect it. More precisely, given a matching problem, we exclude the agents whose first choices are satisfied without any discrepancy among them, and consider the restricted matching problems of the remaining agents. If we reach a state in which all agents are excluded by repeating this procedure, then we should respect the outcome. This property is weaker than stability and is stronger than respect for unanimity (that is also known as weak unanimity). We show that there are no strategy-proof matching rules that respect recursive unanimity. Copyright Springer-Verlag 2013