Characterizing referenda with quorums via strategy-proofness

The paper works with a formal model of referenda, where a finite number of voters can choose between two options and abstention. A referendum will be invalid if too many voters abstain, otherwise the referendum will return one of the two options. We consider quorum rules where an option is chosen if it is preferred by the majority of voters and if at least a certain number of voters (the quorum) votes for the alternative. The paper characterizes these rules as the only referenda which are strategy-proof over certain preferences