Strategic Voting (COMSOC)

Definition

Strategic Voting ( COMSOC)

Strategic voting means choosing a ballot to influence the election outcome, rather than simply reporting one’s true preferences. In the complete-ranking model, a voter with true ranking ${\succ }_i$ may submit ${\hat{\succ }}_i\ne {\succ }_i$, aiming for

$$\underset{\text{outcome of strategic report}}{\underbrace{f({\hat{\succ }}_i,R_{-i})}}{\succ }_i\underset{\text{outcome of truthful report}}{\underbrace{f({\succ }_i,R_{-i})}},$$

where $f$ is a single-winner rule and $R_{-i}$ contains the other voters’ reports. The comparison uses the voter’s unchanged true preferences.

Unlike truthful voting, the ballot is chosen for its anticipated effect. The attempt need not succeed; when the strict improvement above actually holds, it is a successful manipulation.