The Computational Impact of Partial Votes on Strategic Voting
This work addresses the problem of strategic voting in elections with partial votes, which is relevant for computational social choice and election design, though it is incremental as it builds on existing voting rule analyses.
The paper investigates how partial voting affects strategic voting possibilities under three common voting rule modifications, finding that while elimination-style rules like single transferable vote remain unchanged, scoring rules and tournament-based rules can increase strategic opportunities, potentially altering computational complexity.
In many real world elections, agents are not required to rank all candidates. We study three of the most common methods used to modify voting rules to deal with such partial votes. These methods modify scoring rules (like the Borda count), elimination style rules (like single transferable vote) and rules based on the tournament graph (like Copeland) respectively. We argue that with an elimination style voting rule like single transferable vote, partial voting does not change the situations where strategic voting is possible. However, with scoring rules and rules based on the tournament graph, partial voting can increase the situations where strategic voting is possible. As a consequence, the computational complexity of computing a strategic vote can change. For example, with Borda count, the complexity of computing a strategic vote can decrease or stay the same depending on how we score partial votes.