Abstract
It is well known that standard game-theoretic approaches to voting mechanisms lead to a multitude of Nash Equilibria (NE), many of which are counter-intuitive. We focus on truth-biased voters, a model recently proposed to avoid such issues. The model introduces an incentive for voters to be truthful when their vote is not pivotal. This is a powerful refinement, and recent simulations reveal that the surviving equilibria tend to have desirable properties. However, truth-bias has been studied only within the context of plurality, which is an extreme example of k-approval rules with k = 1. We undertake an equilibrium analysis of the complete range of k-approval. Our analysis begins with the veto rule, the other extreme point of k-approval, where each ballot approves all candidates but one. We identify several crucial properties of pure NE for truth-biased veto. These properties show a clear distinction from the setting of truth-biased plurality. We proceed by establishing that deciding on the existence of NE in truth biased veto is an NP-hard problem. We also characterise a tight (in a certain sense) subclass of instances for which the existence of a NE can be decided in poly-time. Finally, we study analogous questions for general k-approval rules.
Original language | English |
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Title of host publication | Algorithmic Decision Theory - 4th International Conference, ADT 2015, Proceedings |
Editors | Toby Walsh |
Publisher | Springer Verlag |
Pages | 451-468 |
Number of pages | 18 |
ISBN (Print) | 9783319231136 |
DOIs | |
State | Published - 2015 |
Event | 4th International Conference on Algorithmic Decision Theory, ADT 2015 - Lexington, United States Duration: 27 Sep 2015 → 30 Sep 2015 |
Publication series
Name | Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) |
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Volume | 9346 |
ISSN (Print) | 0302-9743 |
ISSN (Electronic) | 1611-3349 |
Conference
Conference | 4th International Conference on Algorithmic Decision Theory, ADT 2015 |
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Country/Territory | United States |
City | Lexington |
Period | 27/09/15 → 30/09/15 |
Bibliographical note
Publisher Copyright:© Springer International Publishing Switzerland 2015.