This note supplements the recent work of McCune and Wilson (Public Choice 196(1–2):19–50, 2023) by providing a complete analysis of spoiler effects under both plurality voting and Ranked-Choice Voting in the case of three (potential) candidates. The trick for definitively identifying all spoiler possibilities under both voting rules in the three-candidate case is to partition the set of all three-candidate preference profiles into eight types by cross-classifying the candidates in terms of their plurality status and Condorcet relationships. The resulting typology allows us to identify the winners in all possible two-candidate and three-candidate elections under both voting rules and therefore suffices to identify all spoiler effects. It implies, among other things, that the set of profiles that are vulnerable to spoilers under Ranked-Choice Voting is a proper subset of those vulnerable to spoilers under plurality rule.

本文对 McCune 和 Wilson 最近的工作（Public Choice 196(1–2):19–50, 2023）进行了补充，对多数投票和排名选择投票三种情况下的扰流效应进行了完整分析（潜在） 候选人。在三名候选人的情况下，在两种投票规则下明确识别所有剧透可能性的技巧是，通过根据候选人的多数地位和孔多塞关系对候选人进行交叉分类，将所有三名候选人的偏好概况集合划分为八种类型。由此产生的类型学使我们能够在两种投票规则下确定所有可能的两名候选人和三名候选人选举中的获胜者，因此足以识别所有扰乱效应。除其他外，它意味着，