Strategyproof Tournament Rules for Teams with a Constant Degree of Selfishness
David Pennock, Daniel Schoepflin, and Kangning Wang

TL;DR
This paper introduces a new strategyproof tournament rule that works with intermediate selfishness levels, specifically for λ=11, improving over previous rules that required λ to grow with the number of teams.
Contribution
The authors design a tournament rule that is strategyproof for λ=11, significantly lower than the previous requirement of λ=Ω(n), and introduce a new concept of multiplicative pairwise non-manipulability.
Findings
Strategyproof rule with λ=11 for intermediate selfishness.
A new multiplicative non-manipulability measure with δ=3.5.
Progress towards more manipulation-resistant tournament mechanisms.
Abstract
We revisit the well-studied problem of designing fair and manipulation-resistant tournament rules. In this problem, we seek a mechanism that (probabilistically) identifies the winner of a tournament after observing round-robin play among teams in a league. Such a mechanism should satisfy the natural properties of monotonicity and Condorcet consistency. Moreover, from the league's perspective, the winner-determination tournament rule should be strategyproof, meaning that no team can do better by losing a game on purpose. Past work considered settings in which each team is fully selfish, caring only about its own probability of winning, and settings in which each team is fully selfless, caring only about the total winning probability of itself and the team to which it deliberately loses. More recently, researchers considered a mixture of these two settings with a parameter…
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Taxonomy
TopicsGame Theory and Voting Systems · Logic, Reasoning, and Knowledge · Game Theory and Applications
