In approval-based committee (ABC) voting, the goal is to choose a subset of predefined size of the candidates based on the voters' approval preferences over the candidates. While this problem has attracted significant attention in recent years, the incentives for voters to participate in an election for a given ABC voting rule have been neglected so far. This paper is thus the first to explicitly study this property, typically called participation, for ABC voting rules. In particular, we show that all ABC scoring rules even satisfy group participation, whereas most sequential rules severely fail participation. We furthermore explore several escape routes to the impossibility for sequential ABC voting rules: we prove for many sequential rules that (i) they satisfy participation on laminar profiles, (ii) voters who approve none of the elected candidates cannot benefit by abstaining, and (iii) it is NP-hard for a voter to decide whether she benefits from abstaining.

翻译：在批准制委员会投票中，目标是根据选民对候选人的批准偏好，从预定义规模的候选人集合中选出一个子集。尽管近年来这一问题受到了广泛关注，但在给定ABC投票规则下选民参与选举的激励问题却一直被忽视。因此，本文首次明确研究了ABC投票规则中的这一属性，通常称为参与性。具体而言，我们表明所有ABC评分规则甚至满足群体参与性，而大多数顺序规则严重违背参与性。此外，我们探索了针对顺序ABC投票规则不可行性的若干规避途径：我们证明了许多顺序规则（i）在分层配置上满足参与性，（ii）未批准任何当选候选人的选民不能通过弃权获益，以及（iii）选民判断自己是否从弃权中获益是NP困难的。