Possible bribery in k-approval and k-veto under partial information

Abstract

We study the complexity of possible bribery under nine different notions of partial information for k-Approval and k-Veto. In bribery an external agent tries to change the outcome of an election by changing some voters’ votes. Usually in voting theory, full information is assumed, i.e., the manipulative agent knows the set of candidates, the complete ranking of each voter about the candidates and the voting rule used. In this paper, we assume that the briber only has partial information about the voters’ votes and ask whether the briber can change some voters’ votes such that there is a completion of the partial profile to a full profile such that the briber’s preferred candidate (or most despised candidate in the destructive case) is a winner (not a winner) of the resulting election.