It is known that there are school choice problems without an efficient and stable assignment. We consider comparing assignments in terms of their stability by comparing their sets of blocking (student-school) pairs or comparing their sets of blocking students who are involved in at least one...

We investigate efficient and minimally unstable Pareto improvements over the deferred acceptance (DA) mechanism — a popular school choice mechanism which is stable but not efficient. We show that there is no Pareto improvement over the DA mechanism which is minimally unstable among efficient...

We investigate efficient and minimally unstable Pareto improvements over the deferred acceptance (DA) mechanism-a popular school choice mechanism that is stable but not efficient. We show that there is no Pareto improvement over the DA mechanism that is minimally unstable among efficient...