Affirmative Action in India with Horizontal Reservations

2026-02-09

AI Summary

This study addresses the challenge of fair allocation in India’s affirmative action system, where horizontal and vertical reservation quotas intersect and applicants may belong to multiple horizontal categories simultaneously. To resolve this, the paper proposes a one-to-many matching mechanism that integrates a hierarchical selection rule to identify the optimal set of applicants and an aggregate selection rule encompassing all vertical categories. By combining these rules with a generalized deferred acceptance algorithm, the mechanism achieves, for the first time, a unified guarantee of stability, strategy-proofness, and justified envy-freeness within a hierarchically structured horizontal reservation framework. The authors formally prove that this mechanism is the unique allocation rule satisfying all three properties simultaneously, thereby establishing a robust foundation for mechanism design in complex quota-based resource allocation settings.

Technology Category

• Multiagent Systems: Mechanism Design
• Game Theory and Economic Paradigms: Mechanism Design
• Knowledge Representation and Reasoning: Preferences

Application Category

• User Modeling, Personalization and Recommendation: Fairness-aware retrieval and ranking
• Economics, Online Markets and Human Computation: Fairness, privacy, and diversity in economic environments
• Responsible Web: Human-perceived consequences of algorithmic deployment on the web

Abstract

India implements the world's most complex affirmative action program through vertical and horizontal reservations. Although applicants can belong to at most one vertical category, they can qualify for multiple horizontal reservation categories simultaneously. We examine resource allocation problems in India, where horizontal reservations follow a hierarchical structure within a one-to-all horizontal matching framework. We introduce the hierarchical choice rule and show that it selects the most meritorious set of applicants. We thoroughly analyze the properties of the aggregate choice rule, which comprises hierarchical choice rules across all vertical categories. We show that the generalized deferred acceptance mechanism, when coupled with this aggregate choice rule, is the unique stable and strategy-proof mechanism that eliminates justified envy.

Problem

• Affirmative Action
• Horizontal Reservations
• Resource Allocation
• Matching
• Justified Envy

Innovation

• hierarchical choice rule
• horizontal reservations
• generalized deferred acceptance
• strategy-proofness
• justified envy