we propose a fairness property called P-monotonicity that we would like a matching mechanism to satisfy. We show that it is impossible to have a mechanism which is both stable and P- monotonic. Moreover, we show that it is impossible to have a mechanism which is both efficient and P-monotonic.

We introduce a new matching model to mimic two-sided exchange programs such as tuition and worker exchange, in which each firm has to avoid being a net-exporter of workers. These exchanges use decentralized markets, making it difficult to achieve a balance between exports and imports. We show...