Pinaki Mandal (Arizona State University) will present “Equivalence between Individual and Group Strategy-Proofness under Stability” on March 17th, 2025, at 4:00 PM (CET) via Microsoft Teams. Join the seminar: Meeting Link
Abstract:
When policymakers implement mechanisms in real-world institutions, they often prefer strategy-proof mechanisms over manipulable ones. For example, the Boston School Committee replaced the Boston mechanism with the student-proposing deferred acceptance algorithm in July 2005 to eliminate students’ incentives to misrepresent their preferences over schools. However, strategy-proof mechanisms are not always immune to manipulations by potential coalitions, even if these coalitions are small and easy to coordinate. This issue is mitigated under group strategy-proof mechanisms.
This paper studies group strategy-proofness in stable matching mechanisms within two-sided matching markets, where both sides of the market have strategic agents. In the context of a one-to-one matching market, we demonstrate that incorporating strategy-proofness in any stable matching mechanism not only removes the incentive for individual agents to manipulate but also eliminates the incentive for any group of agents to do so—even if the group includes agents from both sides of the market—thereby ensuring group strategy-proofness. This result holds under sufficiently varied domains. Additionally, we explore the potential extension of these findings to many-to-one matching markets.