On the Distortion Value of Elections with Abstention

Seddighin, Masoud ( Institute for Research in Fundamental Sciences (IPM) -- School of CS) | Latifian, Mohammad (Sharif University of Technology) | Ghodsi, Mohammad (Sharif University of Technology, Institute for Research in Fundamental Sciences (IPM) -- School of CS)

Journal of Artificial Intelligence Research 

In Spatial Voting Theory, distortion is a measure of how good the winner is. It has been proved that no deterministic voting mechanism can guarantee a distortion better than 3, even for simple metrics such as a line. In this study, we wish to answer the following question: how does the distortion value change if we allow less motivated agents to abstain from the election? We consider an election with two candidates and suggest an abstention model, which is a general form of the abstention model proposed by Kirchgässner. Our results characterize the distortion ¨ value and provide a rather complete picture of the model.