Getting More by Knowing Less: Bayesian Incentive Compatible Mechanisms for Fair Division (2306.02040v2)
Abstract: We study fair resource allocation with strategic agents. It is well-known that, across multiple fundamental problems in this domain, truthfulness and fairness are incompatible. For example, when allocating indivisible goods, no truthful and deterministic mechanism can guarantee envy-freeness up to one item (EF1), even for two agents with additive valuations. Or, in cake-cutting, no truthful and deterministic mechanism always outputs a proportional allocation, even for two agents with piecewise constant valuations. Our work stems from the observation that, in the context of fair division, truthfulness is used as a synonym for Dominant Strategy Incentive Compatibility (DSIC), requiring that an agent prefers reporting the truth, no matter what other agents report. In this paper, we instead focus on Bayesian Incentive Compatible (BIC) mechanisms, requiring that agents are better off reporting the truth in expectation over other agents' reports. We prove that, when agents know a bit less about each other, a lot more is possible: BIC mechanisms can guarantee fairness notions that are unattainable by DSIC mechanisms in both the fundamental problems of allocation of indivisible goods and cake-cutting. We prove that this is the case even for an arbitrary number of agents, as long as the agents' priors about each others' types satisfy a neutrality condition. Notably, for the case of indivisible goods, we significantly strengthen the state-of-the-art negative result for efficient DSIC mechanisms, while also highlighting the limitations of BIC mechanisms, by showing that a very general class of welfare objectives is incompatible with Bayesian Incentive Compatibility. Combined these results give a near-complete picture of the power and limitations of BIC and DSIC mechanisms for the problem of allocating indivisible goods.
- Truthful allocation mechanisms without payments: Characterization and implications on fairness. In Proceedings of the 2017 ACM Conference on Economics and Computation, pages 545–562, 2017.
- Allocating indivisible goods to strategic agents: Pure nash equilibria and fairness. Mathematics of Operations Research, 2023.
- Round-robin beyond additive agents: Existence and fairness of approximate equilibria. arXiv preprint arXiv:2301.13652, 2023.
- A truthful cardinal mechanism for one-sided matching. In Proceedings of the Fourteenth Annual ACM-SIAM Symposium on Discrete Algorithms, pages 2096–2113. SIAM, 2020.
- Obvious manipulability of voting rules. In Algorithmic Decision Theory: 7th International Conference, ADT 2021, Toulouse, France, November 3–5, 2021, Proceedings 7, pages 179–193. Springer, 2021.
- Noga Alon. Splitting necklaces. Advances in Mathematics, 63(3):247–253, 1987.
- Approximation algorithms for computing maximin share allocations. ACM Transactions on Algorithms (TALG), 13(4):1–28, 2017.
- Finding fair and efficient allocations for matroid rank valuations. ACM Transactions on Economics and Computation, 9(4):1–41, 2021.
- Fair and truthful mechanisms for dichotomous valuations. In Proceedings of the AAAI Conference on Artificial Intelligence, volume 35, pages 5119–5126, 2021.
- Envy-free and pareto-optimal allocations for agents with asymmetric random valuations. arXiv preprint arXiv:2109.08971, 2021.
- On the existence of envy-free allocations beyond additive valuations. arXiv preprint arXiv:2307.09648, 2023.
- A new solution to the random assignment problem. Journal of Economic Theory, 100(2):295–328, 2001.
- Eric Budish. The combinatorial assignment problem: approximate competitive equilibrium from equal incomes. Journal of Political Economy, 119(6):1061–1103, 2011.
- Truthful and fair mechanisms for matroid-rank valuations. arXiv preprint arXiv:2109.05810, 2021.
- Mechanism design for fair division: allocating divisible items without payments. In Proceedings of the fourteenth ACM conference on Electronic commerce, pages 251–268, 2013.
- The unreasonable fairness of maximum nash welfare. ACM Transactions on Economics and Computation (TEAC), 7(3):1–32, 2019.
- Truth, justice, and cake cutting. Games and Economic Behavior, 77(1):284–297, 2013.
- Ordinal Bayesian incentive compatibility in random assignment model. Review of Economic Design, pages 1–14, 2022.
- Ordinal Bayesian incentive compatible representations of committees. Social Choice and Welfare, 5(4):261–279, 1988.
- Strategyproof allocation of discrete jobs on multiple machines. In Proceedings of the fifteenth ACM conference on Economics and computation, pages 529–546, 2014.
- Fair and efficient memory sharing: Confronting free riders. In Proceedings of the AAAI Conference on Artificial Intelligence, volume 33, pages 1965–1972, 2019.
- AM Fink. A note on the fair division problem. Mathematics Magazine, 37(5):341–342, 1964.
- Efficient money burning in general domains. Theory of Computing Systems, 59(4):619–640, 2016.
- Yuji Fujinaka. A Bayesian incentive compatible mechanism for fair division. 2008.
- Allan Gibbard. Manipulation of voting schemes: a general result. Econometrica: journal of the Econometric Society, pages 587–601, 1973.
- Spliddit: Unleashing fair division algorithms. ACM SIGecom Exchanges, 13(2):41–46, 2015.
- Dominant resource fairness: Fair allocation of multiple resource types. In Nsdi, volume 11, pages 24–24, 2011.
- Fair division with binary valuations: One rule to rule them all. In International Conference on Web and Internet Economics, pages 370–383. Springer, 2020.
- Optimal mechanism design and money burning. In Proceedings of the fortieth annual ACM symposium on Theory of computing, pages 75–84, 2008.
- Strategy-proofness, solidarity, and consistency for multiple assignment problems. International Journal of Game Theory, 30(3):421–435, 2002.
- Shengwu Li. Obviously strategy-proof mechanisms. American Economic Review, 107(11):3257–87, 2017.
- On approximately fair allocations of indivisible goods. In Proceedings 5th ACM Conference on Electronic Commerce (EC-2004), pages 125–131, 2004.
- Hervé Moulin. Implementing efficient, anonymous and neutral social choice functions. Journal of Mathematical Economics, 7(3):249–269, 1980.
- Hervé Moulin. Fair division and collective welfare. MIT press, 2004.
- When do envy-free allocations exist? SIAM Journal on Discrete Mathematics, 34(3):1505–1521, 2020.
- Closing gaps in asymptotic fair division. SIAM Journal on Discrete Mathematics, 35(2):668–706, 2021.
- Partial strategyproofness: Relaxing strategyproofness for the random assignment problem. Journal of Economic Theory, 191:105144, 2021.
- Obvious manipulations in cake-cutting. Social Choice and Welfare, 59(4):969–988, 2022.
- Beyond dominant resource fairness: Extensions, limitations, and indivisibilities. ACM Transactions on Economics and Computation (TEAC), 3(1):1–22, 2015.
- Fair and efficient allocations without obvious manipulations. In Advances in Neural Information Processing Systems, 2022.
- Mark Allen Satterthwaite. Strategy-proofness and arrow’s conditions: Existence and correspondence theorems for voting procedures and social welfare functions. Journal of economic theory, 10(2):187–217, 1975.
- James Schummer. Strategy-proofness versus efficiency on restricted domains of exchange economies. Social Choice and Welfare, 14(1):47–56, 1996.
- Nisarg Shah. Spliddit: two years of making the world fairer. XRDS: Crossroads, The ACM Magazine for Students, 24(1):24–28, 2017.
- Biaoshuai Tao. On existence of truthful fair cake cutting mechanisms. In Proceedings of the 23rd ACM Conference on Economics and Computation, pages 404–434, 2022.
- Obvious manipulations. Journal of Economic Theory, 185:104970, 2020.