A common real-life problem is to fairly allocate a number of indivisible objects and a fixed amount of money among a group of agents. Fairness requires that each agent weakly prefers his consumption bundle to any other agent's bundle. In this context, fairness is incompatible with budget-balance...

This paper studies the problem of assigning a set of indivisible objects to a set of agents when monetary transfers are not allowed and agents reveal only ordinal preferences, but random assignments are possible. We offer two characterizations of the probabilistic serial mechanism, which assigns...

In a matching problem between students and schools, a mechanism is said to be robustly stable if it is stable, strategy-proof, and immune to a combined manipulation, where a student first misreports her preferences and then blocks the matching that is produced by the mechanism. We find that even...

I develop two related solution concepts, equilibrium coalitional behavior and credible equilibrium coalitional behavior, which capture foresight and impose the requirement that each coalition in a sequence of coalitional moves chooses optimally among all its available options. The model does not...

A new mechanism was introduced in New York City and Boston to assign students to public schools. This mechanism was advocated for its superior fairness property, besides others. We introduce a new framework for school-choice problems and two notions of fairness in lottery design based on ex-ante...

We investigate a normative theory of incomplete preferences in the context of preliminary screening procedures. We introduce a theory of ranking in the presence of objectively incomparable marginal contributions (apples and oranges). Our theory recommends benchmarking, a method under which an...

This paper introduces a model of coalition formation with claims. It assumes that agents have claims over the outputs they could produce by forming coalitions. Outputs, insufficient to meet the claims and are rationed by a rule whose proposals of division induce each agent to rank the coalitions...

We prove a general possibility result for collective decision problems where individual allocations are one-dimensional, preferences are single-peaked (strictly convex), and feasible allocation profiles cover a closed convex set. Special cases include the celebrated median voter theorem (Black...

The case for progressive income taxation is often based on the classic result of Jakobsson, 1976 and Fellman, 1976, according to which progressive and only progressive income taxes - in the sense of increasing average tax rates on income - ensure a reduction in income inequality. This result has...