8,730 research outputs found
More Natural Models of Electoral Control by Partition
"Control" studies attempts to set the outcome of elections through the
addition, deletion, or partition of voters or candidates. The set of benchmark
control types was largely set in the seminal 1992 paper by Bartholdi, Tovey,
and Trick that introduced control, and there now is a large literature studying
how many of the benchmark types various election systems are vulnerable to,
i.e., have polynomial-time attack algorithms for.
However, although the longstanding benchmark models of addition and deletion
model relatively well the real-world settings that inspire them, the
longstanding benchmark models of partition model settings that are arguably
quite distant from those they seek to capture.
In this paper, we introduce--and for some important cases analyze the
complexity of--new partition models that seek to better capture many real-world
partition settings. In particular, in many partition settings one wants the two
parts of the partition to be of (almost) equal size, or is partitioning into
more than two parts, or has groups of actors who must be placed in the same
part of the partition. Our hope is that having these new partition types will
allow studies of control attacks to include such models that more realistically
capture many settings
Complexity of Manipulative Actions When Voting with Ties
Most of the computational study of election problems has assumed that each
voter's preferences are, or should be extended to, a total order. However in
practice voters may have preferences with ties. We study the complexity of
manipulative actions on elections where voters can have ties, extending the
definitions of the election systems (when necessary) to handle voters with
ties. We show that for natural election systems allowing ties can both increase
and decrease the complexity of manipulation and bribery, and we state a general
result on the effect of voters with ties on the complexity of control.Comment: A version of this paper will appear in ADT-201
Anyone but Him: The Complexity of Precluding an Alternative
Preference aggregation in a multiagent setting is a central issue in both
human and computer contexts. In this paper, we study in terms of complexity the
vulnerability of preference aggregation to destructive control. That is, we
study the ability of an election's chair to, through such mechanisms as
voter/candidate addition/suppression/partition, ensure that a particular
candidate (equivalently, alternative) does not win. And we study the extent to
which election systems can make it impossible, or computationally costly
(NP-complete), for the chair to execute such control. Among the systems we
study--plurality, Condorcet, and approval voting--we find cases where systems
immune or computationally resistant to a chair choosing the winner nonetheless
are vulnerable to the chair blocking a victory. Beyond that, we see that among
our studied systems no one system offers the best protection against
destructive control. Rather, the choice of a preference aggregation system will
depend closely on which types of control one wishes to be protected against. We
also find concrete cases where the complexity of or susceptibility to control
varies dramatically based on the choice among natural tie-handling rules.Comment: Preliminary version appeared in AAAI '05. Also appears as
URCS-TR-2005-87
Normalized Range Voting Broadly Resists Control
We study the behavior of Range Voting and Normalized Range Voting with
respect to electoral control. Electoral control encompasses attempts from an
election chair to alter the structure of an election in order to change the
outcome. We show that a voting system resists a case of control by proving that
performing that case of control is computationally infeasible. Range Voting is
a natural extension of approval voting, and Normalized Range Voting is a simple
variant which alters each vote to maximize the potential impact of each voter.
We show that Normalized Range Voting has among the largest number of control
resistances among natural voting systems
Diversity and the Power of the Elites inDemocraticSocieties: A Model and a Test.
This paper analyzes whether political outcomes in local democracies are determinedby the preferences of the median - typically poor - agents or whether they reflect thewishes of the wealthy elites. A model shows that when politicians belonging todifferent groups can form coalitions, the wealthy elites' influence on policy choices isendogenously higher when there is diversity in preferences among the poor. In linewith the theoretical predictions, the pattern of public good provision by localgovernments in Indonesia reveals that when individuals have different preferences— here due to different ethnicities — democratic policy outcomes are closer to thepreferences of the elites, rather than the preferences of the poor majority.
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