How does uncertainty about other voters determine a strategic vote?

TL;DR

This paper develops a framework for strategic voting under uncertainty about other voters' preferences and knowledge, analyzing how such uncertainty influences manipulation, equilibrium, and voting outcomes.

Contribution

It introduces a formal model of strategic voting with incomplete information, including notions of manipulation, equilibrium, and the impact of information updates.

Findings

Profiles with identical true preferences can have different equilibria due to knowledge differences

Some manipulations are robust under information updates, others are not

Provides a formal logical framework for epistemic voting analysis

Abstract

We propose a framework for strategic voting when a voter may lack knowledge about the preferences of other voters, or about other voters' knowledge about her own preference. In this setting we define notions of manipulation, equilibrium, and dominance, under uncertainty. We provide scenarios wherein the profiles of true preferences are the same but the equilibrium profiles are different, because the voters have different knowledge about other voters. We also model actions that change such uncertainty about preferences, such as a voter revealing her preference. We show that some forms of manipulation and equilibrium are preserved under such uncertainty updates and others not. We then formalize epistemic voting terminology in a logic. Our aim is to provide the epistemic background for the analysis and design of voting rules that incorporate uncertainty.