Theoretical Economics Papers

ALT When allocating indivisible goods, the maximum Nash welfare rule is known to be the unique welfarist rule satisfying envy-freeness up to one good. We strengthen this characterization by showing that envy-freeness up to one good can be replaced by substantially weaker fairness requirements: envy-freeness up to k goods or proportionality up to k goods, for any fixed k. Our characterization holds even for profiles with identical goods.

ALT We introduce a mediator to a communication setting with verifiable (hard) evidence and characterize precisely when mediation can induce every obedient outcome–every type-contingent distribution of actions that the receiver is willing to follow–including the outcome that delivers the sender's commitment (Bayesian persuasion) payoff. For both type-independent and general preferences, it is necessary for each type to have a message he alone can send. This is also sufficient for type-independent preferences, whereas the general case also requires a particular alignment of the types' utilities. We also rank evidence structures by the distributions of actions conditional on the sender's type that they can induce at (mediated) equilibrium, through garbling conditions analogous to Blackwell's comparison of experiments.

ALT I study the optimality of selling K heterogeneous objects to a buyer with private values through a quantity menu: the seller posts a price for each number of objects, and the buyer chooses a quantity, pays its price, and selects any objects up to that quantity. I propose a pricing method that aggregates critical values for second differences of quantity values (the highest values attainable at each quantity). Critical values can be determined separately when each second difference's conditional inverse-hazard ratio depends only on that difference. For additive values, I show that the resulting menu is optimal among all incentive-compatible and individually rational mechanisms under explicit distributional and support conditions, including ex ante symmetry across object labels. A separate result applies the same pricing method to obtain an optimal menu for nonadditive bundle values without ex ante symmetry, assuming free disposal, independence between the quantity-value vector and the v

ALT Variation in grading standards across instructors who teach the same students is evidence of a moral hazard problem, whether or not grades are inflated. The optimal standard is the same for every section of a course, yet grades vary widely across sections. We present a principal-agent model in which instructors who know the optimal standard still depart from it, leniently or harshly, depending on their incentives. Penalizing deviations from the department average leaves the average unchanged but compresses grading variance, which raises student welfare. Disclosing the same information to students instead increases grading variance.

ALT We study the steady states of games played recurrently within large anonymous populations of players who receive partial ex-post feedback about the play of their opponents. Departing from the classical Bayesian account, players do not trust their conjectures as a correct description of the strategic environment but consider them as approximations of a reality that is only partially modeled and partially observed. We introduce games with feedback and uncertainty attitudes, in which the normal-form structure is enriched with a profile of feedback functions and, for each player, a preference functional that encodes aversion to misspecification and to ambiguity. The induced misspecification sensitive criterion contains the variational, maxmin, and smooth-ambiguity evaluations as special cases and collapses to expected utility when beliefs are unambiguous and the player is neutral to misspecification. The appropriate steady-state notion for such games is the Self-Confirming Equilibrium unde

ALT We study sharp bounds on equilibrium behavior in Bayesian games when players may make mistakes. Under strategic complementarities, the set of behavioral perfect equilibria has a largest and a smallest element, both in pure strategies. We ask when these bounds are monotone and how they depend on the way mistakes are made. For monotone supermodular games, we consider limits of equilibria under increasing perturbations, in the sense that conditional tremble distributions have full support and increase stochastically with type. We show that the largest and smallest perfect equilibria exist, which are pure and monotone. Under the general perfection notion, the extremal perfect equilibria continue to be monotone in the setting with finite actions. With infinite actions, the extremal perfect equilibria can be nonmonotone, and the set of perfect monotone equilibria can even lack extrema.

ALT Convexity of preferences is a pervasive assumption in economic analysis, so it is important to understand how this property is revealed in data. In this paper, we develop a method to test for convexity given partial preference information in the form of weak and strict incomplete orders. We characterize the pairs that can be extended to convex preferences and provide an efficient algorithm to verify this property. Requiring the convex preference to align with an order that satisfies independence, such as the Euclidean order or stochastic dominance, does not complicate the test. We apply our results to consumer demand, choice under risk and uncertainty, and preferences over information, and establish conditions under which upper semicontinuity or continuity can also be obtained. We identify environments in which convexity imposes no additional restrictions beyond rationality, extending Afriat-type results to infinite data and co-convex budgets and establishing a convex version of exact

ALT This paper revisits the consumer search and price competition model of Wolinsky (1986). Suppose that the market has a finite number of firms, and the match value distribution function and survival function are both log-concave. Then, there is a unique symmetric pure-strategy equilibrium price with active consumer search. Two applications are discussed.

ALT Generative AI can lower the cost of producing polished application materials without improving applicants' abilities to do the job. We study an employer who observes qualifications and work history, summarized by observable quality, but must infer other job-relevant attributes from reports that applicants can manipulate at costs that depend on privately known manipulation ability. The employer commits to a hiring rule under a capacity constraint, and we evaluate rules by match value net of applicants' manipulation costs. We show that, as manipulation ability becomes increasingly dispersed among applicants with the same observable quality, socially optimal hiring converges to selection on observable quality alone, a phenomenon we call strategic feature collapse. To capture the remaining welfare gain from reports, we construct a simple dual-track mechanism that directly admits applicants with high observable quality and offers some otherwise excluded applicants a report-based route to ad

ALT Sustaining efficient trade under private information requires external subsidies. Although a designer cannot avoid deficits on average, they can control exposure. We characterize efficient and truthful mechanisms that minimize the worst-case deficit in markets with many buyers and sellers, under interim participation. This problem is dual to maximizing expected trade surplus under correlation ambiguity, with constraints on submarkets with one agent removed. In bilateral trade, the best deficit ceiling is the competitive surplus in a benchmark continuum market, achieved by a "competitive pivot mechanism". In larger markets, optimal mechanisms are characterized in terms of worst-case residual welfare contributions, but solutions exhibit a complex combinatorial structure. We obtain explicit guarantees under natural participation charge restrictions and establish how the best deficit excess decays as market thickens. Our duality characterization is general and extends to many mechanism des