Fair allocation of indivisible goods among two agents

One must allocate a finite set of indivisible goods among two agents without monetary compensation. We impose Pareto-efficiency, anonymity, a weak notion of no-envy, a welfare lower bound based on each agent’s ranking of the sets of goods, and a monotonicity property relative to changes in agents’ preferences. We prove that there is a rule satisfying these axioms. If there are three goods, it is the only rule, with one of its subcorrespondences, satisfying each fairness axiom and not discriminating between goods. Further, we confirm the clear gap between these economies and those with more than two agents.indivisible goods, no monetary compensation, no-envy, lower bound, preference-monotonicity

Characterizing Welfare-egalitarian Mechanisms with Solidarity When Valuations are Private Information

In the problem of assigning indivisible goods and monetary transfers, we characterize welfare-egalitarian mechanisms (that are decision-efficient and incentive compatible) with an axiom of solidarity under preference changes and a fair ranking axiom of order preservation. This result is in line with characterizations of egalitarian rules with solidarity in other economic models. We also show that we can replace order-preservation with egalitarian-equivalence or no-envy (on the subadditive domain) and still characterize the welfare-egalitarian class. We show that, in the model we consider, the welfare-egalitarian mechanisms appear to be the best candidates to satisfy several different fairness and solidarity requirements as well as generating bounded deficits.egalitarianism, solidarity, order preservation, egalitarian-equivalence, no-envy, distributive justice, NIMBY problems, imposition of tasks, allocation of indivisible (public) goods and money, the Groves mechanisms, strategy-proofness

Equivalence of Resource/Opportunity Egalitarianism and Welfare Egalitarianism in Quasilinear Domains

We study the allocation of indivisible goods when monetary transfers are possible and preferences are quasilinear. We show that the only allocation mechanism (upto Pareto-indifference) that satisfies the axioms supporting resource and opportunity egalitarianism is the one that equalizes the welfares. We present alternative characterizations, and budget properties of this mechanism and discuss how it would ensure fair compensation in government requisitions and condemnations.egalitarianism, egalitarian-equivalence, no-envy, distributive justice, allocation of indivisible goods and money, fair auctions, the Groves mechanisms, strategy-proofness, population monotonicity, cost monotonicity, government requisitions, eminent domain

Welfare Bounds in a Growing Population

We study the allocation of collectively owned indivisible goods when monetary transfers are possible. We restrict our attention to incentive compatible mechanisms which allocate the goods efficiently. Among these mechanisms, we characterize those that respect welfare lower bounds. The main characterization involves the identical-preferences lower-bound: each agent should be at least as well off as in an hypothetical economy where all agents have the same preference as hers, no agent envies another, and the budget is balanced. This welfare lower-bound grants agents equal rights/responsibilities over the jointly owned resources but insures agents against the heterogeneity in preferences. We also study the implications of imposing variable population axioms together with welfare bounds.collective ownership, allocation of indivisible goods and money, NIMBY problems, imposition of tasks, the Groves mechanisms, the identical-preferences lower-bound, individual rationality, the stand-alone lower-bound, k-fairness, population monotonicity

An axiomatic approach to the measurement of envy

We characterize a class of envy-as-inequity measures. There are three key axioms. Decomposability requires that overall envy is the sum of the envy within and between subgroups. The other two axioms deal with the two-individual setting and specify how the envy measure should react to simple changes in the individuals’ commodity bundles. The characterized class measures how much one individual envies another individual by the relative utility difference (using the envious’ utility function) between the bundle of the envied and the bundle of the envious, where the utility function that must be used to represent the ordinal preferences is the ‘ray’ utility function. The class measures overall envy by the sum of these (transformed) relative utility differences. We discuss our results in the light of previous contributions to envy measurement and multidimensional inequality measurement

Bidding for envy-freeness: A procedural approach to n-player fair-division problems

We develop a procedure for implementing an efficient and envy-free allocation of m objects among n individuals with the possibility of monetary side-payments. The procedure eliminates envy by compensating envious players. It is fully descriptive and says explicitly which compensations should be made, and in what order. Moreover, it is simple enough to be carried out without computer support. We formally characterize the properties of the procedure, show how it establishes envy-freeness with minimal resources, and demonstrate its application to a wide class of fair-division problems.fair-division procedures, envy-freeness

Double implementation in a market for indivisible goods with a price constraint

I consider the problem of assigning agents to indivisible objects, in which each agent pays a price for his object and all prices sum to a given constant. The objective is to select an assignment-price pair that is envy- free with respect to the agents' true preferences. I propose a simple mechanism whereby agents announce valuations for all objects and an envy-free allocation is selected with respect to these announced preferences. I prove that the proposed mechanism implements both in Nash and strong Nash equilibrium the set of true envy-free allocations

Matching under Preferences

Matching theory studies how agents and/or objects from different sets can be matched with each other while taking agents\u2019 preferences into account. The theory originated in 1962 with a celebrated paper by David Gale and Lloyd Shapley (1962), in which they proposed the Stable Marriage Algorithm as a solution to the problem of two-sided matching. Since then, this theory has been successfully applied to many real-world problems such as matching students to universities, doctors to hospitals, kidney transplant patients to donors, and tenants to houses. This chapter will focus on algorithmic as well as strategic issues of matching theory. Many large-scale centralized allocation processes can be modelled by matching problems where agents have preferences over one another. For example, in China, over 10 million students apply for admission to higher education annually through a centralized process. The inputs to the matching scheme include the students\u2019 preferences over universities, and vice versa, and the capacities of each university. The task is to construct a matching that is in some sense optimal with respect to these inputs. Economists have long understood the problems with decentralized matching markets, which can suffer from such undesirable properties as unravelling, congestion and exploding offers (see Roth and Xing, 1994, for details). For centralized markets, constructing allocations by hand for large problem instances is clearly infeasible. Thus centralized mechanisms are required for automating the allocation process. Given the large number of agents typically involved, the computational efficiency of a mechanism's underlying algorithm is of paramount importance. Thus we seek polynomial-time algorithms for the underlying matching problems. Equally important are considerations of strategy: an agent (or a coalition of agents) may manipulate their input to the matching scheme (e.g., by misrepresenting their true preferences or underreporting their capacity) in order to try to improve their outcome. A desirable property of a mechanism is strategyproofness, which ensures that it is in the best interests of an agent to behave truthfully