An extension rule assigns to each fractional tournament x (specifying, for every pair of social alternatives a and b, the proportion xab of voters who prefer a to b) a random choice function y (specifying a collective choice probability distribution for each subset of alternatives), which...

We propose a class of decisive collective choice rules that rely on a linear ordering to partition the majority relation into two acyclic relations. The first of these relations is used to pare down the set of the feasible alternatives into a shortlist while the second is used to make a final...

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...