Groups of voters have more possibilities to influence the voting result than separate individuals. However, there is a problem with coordinating their actions. This paper considers manipulation by groups of voters who have the same preferences. If a voting result is more preferable for voters of a particular group provided that all its members use the same strategy (report the same insincere preference), then each of these members has an incentive to manipulate. If there is a chance that they will become worse off in case only a subset of the whole group manipulates, then manipulation is unsafe. For several voting rules we study conditions on the numbers of voters and alternatives which allow for an unsafe manipulation or which make manipulation always safe.

选民群体比单独的个人更有可能影响投票结果。然而，他们的行动协调存在问题。本文考虑了具有相同偏好的选民群体的操纵。如果投票结果对特定群体的选民来说更有利，前提是其所有成员都使用相同的策略（报告相同的不真诚的偏好），那么这些成员中的每一个都有操纵的动机。如果整个群体中只有一小部分人进行操纵，他们的境况可能会变得更糟，那么操纵就是不安全的。对于一些投票规则，我们研究了选民数量的条件以及允许不安全操纵或使操纵始终安全的替代方案。