An important problem in computational social choice theory is the complexity of undesirable behavior among agents, such as control, manipulation, and bribery in election systems. These kinds of voting strategies are often tempting at the individual level but disastrous for the agents as a whole. Creating election systems where the determination of such strategies is difficult is thus an important goal.
An interesting set of elections is that of scoring protocols. Previous work in this area has demonstrated the complexity of misuse in cases involving a fixed number of candidates, and of specific election systems on unbounded number of candidates such as Borda. In contrast, we take the first step in generalizing the results of computational complexity of election misuse to cases of infinitely many scoring protocols on an unbounded number of candidates. Interesting families of systems include $k$-approval and $k$-veto elections, in which voters distinguish $k$ candidates from the candidate set.
Our main result is to partition the problems of these families based on their complexity. We do so by showing they are polynomial-time computable, NP-hard, or polynomial-time equivalent to another problem of interest. We also demonstrate a surprising connection between manipulation in election systems and some graph theory problems.
Estimating the Margin of Victory of an Election using Sampling
Indian Institute of Science（印度科学学院）
选举的胜率是衡量选举结果是否稳健的有用指标。它也起着至关重要的作用，在选举后的审计，投票等各种算法的样本量确定在这项工作中，我们提出了有效的抽样为基础的算法，估计选举的胜利幅度。更正式地说，我们引入了\textsc{$(c, ε, δ)$--Margin of Victory}问题，其中给定$\mathcal{E}$对$n$选民的选举，目标是在$c MoV(\mathcal{E})+εn$的附加因子内估计$\mathcal{E}$的胜利$M(\mathcal{E})$的差距。我们研究了\textsc{$(c, ε, δ)$--Margin of Victory}问题，许多常用的投票规则，包括评分规则，批准，Bucklin，最大，和科普兰$^α.$我们观察到，即使是计算胜利的保证金的投票规则是NP-硬，可能存在有效的抽样为基础的算法，观察到的情况下，最大和科普兰$^α$投票规则。
Computing Thiele Rules on Interval Elections and their Generalizations
Department of Mathematics and Computer Science（数学与计算机科学系）；Eindhoven University of Technology（埃因霍温理工大学）；School of Computer Science, and Department of Mathematics and Statistics（计算机科学学院和数学与统计学系）；McGill University（麦吉尔大学）
On the Complexity of Winner Determination and Strategic Control in Conditional Approval Voting
Athens University of Economics and Business（雅典经济与商业大学）；Archimedes, Athena Research Center（阿基米德、雅典研究中心）；Input Output Global (IOG)（输入输出全球（IOG））；University of Warsaw（华沙大学）
Tata Institute of Fundamental Research（塔塔基础研究所）；Indian Institute of Technology, Gandhinagar（甘地讷格尔印度理工学院）；Indian Institute of Science, Bangalore（班加罗尔印度科学院）
