Visibly Fair Mechanisms

2025-06-23

AI Summary

In priority-based allocation, eliminating justified envy typically requires the serial dictatorship (SD) mechanism, yet SD often violates designers’ objectives. Method: We introduce “visible fairness”—a novel fairness notion requiring mechanisms to satisfy fairness only with respect to the (potentially intentionally incomplete) preference information they actually elicit—thereby relaxing SD’s rigidity. Contribution/Results: We establish the first theoretical framework for visible fairness, unifying the trade-offs among fairness, information efficiency, and strategyproofness; fully characterize the structure of visible-fair mechanisms; provide necessary and sufficient conditions for strategyproofness; and design efficient, strategyproof mechanisms for multiple distributional objectives. This work extends the theoretical frontier of fair allocation and provides a new paradigm for mechanism design that simultaneously achieves fairness, efficiency, and practical implementability.

Technology Category

• Game Theory and Economic Paradigms: Fair Division
• Multiagent Systems: Mechanism Design
• Computer Vision: Bias, Fairness & Privacy

Application Category

• Economics, Online Markets and Human Computation: Fairness, privacy, and diversity in economic environments
• User Modeling, Personalization and Recommendation: Fairness-aware retrieval and ranking
• Security and Privacy: Data transparency and provenance

Abstract

Priority-based allocation of individuals to positions are pervasive, and elimination of justified envy is often, an absolute requirement. This leaves serial dictatorship (SD) as the only rule that avoids justified envy under standard direct mechanisms. What if SD outcomes are undesirable from a designer's perspective? We propose visible fairness, which demands fairness relative to the (potentially purposefully incomplete) preference information the mechanism elicits. Visibly fair mechanisms generalize SD; we fully characterize them and provide necessary and sufficient conditions for strategy-proofness. We show how to apply these results to design strategy-proof visibly fair rules that satisfy a broad class of distributional objectives. Visible fairness, however, results in a new information-efficiency trade-off: meeting distributional goals leads to the avoidance of eliciation of information about preferences that could prevent inefficiencies.

Problem

• Ensuring fairness in priority-based allocation without justified envy
• Designing strategy-proof visibly fair mechanisms for distributional objectives
• Balancing information-efficiency trade-offs in preference elicitation

Innovation

• Visible fairness generalizes serial dictatorship
• Strategy-proof visibly fair rules designed
• New information-efficiency trade-off introduced