The complexity of controlling candidate-sequential elections

  title={The complexity of controlling candidate-sequential elections},
  author={Edith Hemaspaandra and Lane A. Hemaspaandra and J{\"o}rg Rothe},
  journal={Theor. Comput. Sci.},
Complexity of control by partitioning veto elections and of control by adding candidates to plurality elections
It is observed that a reduction from the literature showing the parameterized complexity of control by adding candidates to plurality elections, parameterized by the number of voters, is technically flawed, and it is shown how this reduction can be adapted to make it correct.
Closing the Gap of Control Complexity in Borda Elections : Solving Twelve Open Cases 1
We consider the problem of control in elections where an election chair seeks to either make a designated candidate win, or prevent her from winning, via actions such as adding, deleting, or
The Complexity of Online Bribery in Sequential Elections
It is shown that even for election systems whose winner-determination problem is polynomial-time computable, an online, sequential setting may vastly increase the complexity of bribery, in fact jumping the problem up to completeness for high levels of thePolynomial hierarchy or even PSPACE.
Election-Attack Complexity for More Natural Models
A model of electoral control in the setting where some of the voters act strategically (i.e., are manipulators) is introduced, and both the case where the agent controlling the election and the manipulators share a goal, and the cases where they have competing goals are considered.
Solving Seven Open Problems of Offline and Online Control in Borda Elections
This work reduces the number of missing cases by pinpointing the complexity of three control scenarios for Borda elections, including some that arguably are among the practically most relevant ones.
Borda Count in Collective Decision Making: A Summary of Recent Results
It is described how Borda can be used to maximize social welfare when indivisible goods are to be allocated to agents with ordinal preferences and the use of Borda in forming coalitions of players in a certain type of hedonic game is illustrated.
Dynamic Proportional Rankings
This work proposes generalizations of well-known aggregation rules to this setting and studies their monotonicity and proportionality properties, and evaluates the performance of these rules experimentally, using realistic probabilistic assumptions on the selection procedure.
How Can We Model Emotional and Behavioral Dynamics in Collective Decision Making?
  • J. Rothe
  • Psychology
    The Future of Economic Design
  • 2019
It is proposed to model collective decision making more dynamically and by taking into account how the agents’ preferences and behavior evolve over time and based on their emotions.
Perpetual Voting: Fairness in Long-Term Decision Making
This paper explores the proposed voting rules via an axiomatic analysis as well as a quantitative evaluation by computer simulations and identifies two perpetual voting rules as particularly recommendable in long-term collective decision making.


The complexity of online voter control in sequential elections
A framework that models online voter control in sequential elections and obtains completeness for coNP in the deleting/adding cases with a bounded deletion/addition limit and for NP in the partition cases with an additional restriction is introduced.
The Complexity of Online Manipulation of Sequential Elections
Online Voter Control in Sequential Elections
This work introduces a framework that models online voter control in sequential elections and shows that for plurality, online control by deleting or adding voters is in P, and for partitioning voters is coNP-hard.
More Natural Models of Electoral Control by Partition
It is the hope that having these new partition types will allow studies of control attacks to include such models that more realistically capture many settings, and for some important cases analyze the complexity of these models.
When are elections with few candidates hard to manipulate?
This article characterize the exact number of candidates for which manipulation becomes hard for the plurality, Borda, STV, Copeland, maximin, veto, plurality with runoff, regular cup, and randomized cup protocols and shows that for simpler manipulation problems, manipulation cannot be hard with few candidates.
Control and Bribery in Voting
This chapter surveys results on the complexity of control and bribery in elections, providing an overview of the specific problems studied, sketching sample proofs, and reviewing some approaches to dealing with the computational hardness of these control and bribes problems.
Anyone but him: The complexity of precluding an alternative
Equilibria of plurality voting with abstentions
This paper considers the setting where all voters are strategic, and provides a complete analysis of the setting with two candidates, and shows that for three or more candidates the equilibria of sequential voting may behave in a counterintuitive manner.
Control in the Presence of Manipulators: Cooperative and Competitive Cases
It is proved that for approval and plurality elections, the complexity of even competitive clashes between a controller and manipulators falls far below high bounds, even as low as polynomial time, and for a Borda-voting case it is shown that such clashes raise the complexity unless NP = coNP.
Llull and Copeland Voting Computationally Resist Bribery and Constructive Control
Among systems with a polynomial-time winner problem, Copeland voting is the first natural election system proven to have full resistance to constructive control and vulnerability results for microbribery are proven via a novel technique involving min-cost network flow.