Results 1 
7 of
7
Weighted Electoral Control
"... www.cs.rochester.edu/∼lane Although manipulation and bribery have been extensively studied under weighted voting, there has been almost no work done on election control under weighted voting. This is unfortunate, since weighted voting appears in many important natural settings. In this paper, we stu ..."
Abstract

Cited by 10 (6 self)
 Add to MetaCart
(Show Context)
www.cs.rochester.edu/∼lane Although manipulation and bribery have been extensively studied under weighted voting, there has been almost no work done on election control under weighted voting. This is unfortunate, since weighted voting appears in many important natural settings. In this paper, we study the complexity of controlling the outcome of weighted elections through adding and deleting voters. We obtain polynomialtime algorithms, NPcompleteness results, and for many NPcomplete cases, approximation algorithms. Our work shows that for quite a few important cases, either polynomialtime exact algorithms or polynomialtime approximation algorithms exist.
A smooth transition from powerlessness to absolute power. http://www.cs.cmu.edu/˜arielpro/papers/ phase.pdf
, 2012
"... We study the phase transition of the coalitional manipulation problem for generalized scoring rules. Previously it has been shown that, under some conditions on the distribution of votes, if the number of manipulators is o ( √ n), where n is the number of voters, then the probability that a random ..."
Abstract

Cited by 8 (2 self)
 Add to MetaCart
(Show Context)
We study the phase transition of the coalitional manipulation problem for generalized scoring rules. Previously it has been shown that, under some conditions on the distribution of votes, if the number of manipulators is o ( √ n), where n is the number of voters, then the probability that a random profile is manipulable by the coalition goes to zero as the number of voters goes to infinity, whereas if the number of manipulators is ω ( √ n), then the probability that a random profile is manipulable goes to one. Here we consider the critical window, where a coalition has size c √ n, and we show that as c goes from zero to infinity, the limiting probability that a random profile is manipulable goes from zero to one in a smooth fashion, i.e., there is a smooth phase transition between the two regimes. This result analytically validates recent empirical results, and suggests that deciding the coalitional manipulation problem may not be computationally hard in practice. 1
The Complexity of Losing Voters
"... We consider the scenario of a parliament that is going to vote on a specific important issue. The voters are grouped in parties, and all voters of a party vote in the same way. The expected winner decision is known, because parties declare their intentions to vote, but before the actual vote takes p ..."
Abstract

Cited by 3 (1 self)
 Add to MetaCart
(Show Context)
We consider the scenario of a parliament that is going to vote on a specific important issue. The voters are grouped in parties, and all voters of a party vote in the same way. The expected winner decision is known, because parties declare their intentions to vote, but before the actual vote takes place some voters may leave the leading party to join other parties. We investigate the computational complexity of the problem of determining how many voters need to leave the leading party before the winner changes. We consider both positional scoring rules (plurality, veto, kapproval, kveto, Borda) and Condorcetconsistent methods (maximin, Copeland), and we study two versions of the problem: a pessimistic one, where we want to determine the maximal number of voters that can leave the leading party without changing the winner; and an optimistic one, where we want the minimal number of voters that must leave the leading party to be sure the winner will change. These two numbers provide a measure of the threat to the expected winner, and thus to the leading party, given by losing some voters. We show that for many positional scoring rules these problems are easy (except for the optimistic version with kapproval, for k at least 3, and Borda). Instead, for Condorcetconsistent rules, they are both computationally difficult, with both Maximin and Copeland.
Generalized Scoring Rules: A Framework That Reconciles Borda and Condorcet
"... Generalized scoring rules [Xia and Conitzer 08] are a relatively new class of social choice mechanisms. In this paper, we survey developments in generalized scoring rules, showing that they provide a fruitful framework to obtain general results, and also reconcile the Borda approach and Condorcet ap ..."
Abstract

Cited by 2 (1 self)
 Add to MetaCart
Generalized scoring rules [Xia and Conitzer 08] are a relatively new class of social choice mechanisms. In this paper, we survey developments in generalized scoring rules, showing that they provide a fruitful framework to obtain general results, and also reconcile the Borda approach and Condorcet approach via a new social choice axiom. We comment on some highlevel ideas behind GSRs and their connection to Machine Learning, and point out some ongoing work and future directions.
Generalized Scoring Rules: A Framework That
"... Generalized scoring rules [Xia and Conitzer 08] are a relatively new class of social choice mechanisms. In this paper, we survey developments in generalized scoring rules, showing that they provide a fruitful framework to obtain general results, and also reconcile the Borda approach and Condorcet ap ..."
Abstract
 Add to MetaCart
Generalized scoring rules [Xia and Conitzer 08] are a relatively new class of social choice mechanisms. In this paper, we survey developments in generalized scoring rules, showing that they provide a fruitful framework to obtain general results, and also reconcile the Borda approach and Condorcet approach via a new social choice axiom. We comment on some highlevel ideas behind GSRs and their connection to Machine Learning, and point out some ongoing work and future directions.
General Terms
"... We prove that for any integer generalized scoring rules (GSRs), winner determination and computing a wide range of strategic behavior are fixedparameter tractable (FPT) w.r.t. the number of alternatives. Categories and Subject Descriptors ..."
Abstract
 Add to MetaCart
(Show Context)
We prove that for any integer generalized scoring rules (GSRs), winner determination and computing a wide range of strategic behavior are fixedparameter tractable (FPT) w.r.t. the number of alternatives. Categories and Subject Descriptors