On the Average Minimum Size of a Manipulating Coalition

Asymptotics of the minimum manipulating coalition size for positional voting rules under IC behaviour

2 5 Fe b 20 07 Asymptotics of the minimum manipulating coalition size for positional voting rules under IC behaviour

We consider the problem of manipulation of elections using positional voting rules under Impartial Culture voter behaviour. We consider both the logical possibility of coalitional manipulation, and the number of voters that must be recruited to form a manipulating coalition. It is shown that the manipulation problem may be well approximated by a very simple linear program in two variables. This...

Asymptotics of the minimum manipulating coalition size for positional voting rules under impartial culture behaviour

We consider the problem of manipulation of elections using positional voting rules under Impartial Culture voter behaviour. We consider both the logical possibility of coalitional manipulation, and the number of voters that must be recruited to form a manipulating coalition. It is shown that the manipulation problem may be well approximated by a very simple linear program in two variables. This...

Where Are the Really Hard Manipulation Problems? The Phase Transition in Manipulating the Veto Rule

Voting is a simple mechanism to aggregate the preferences of agents. Many voting rules have been shown to be NP-hard to manipulate. However, a number of recent theoretical results suggest that this complexity may only be in the worst-case since manipulation is often easy in practice. In this paper, we show that empirical studies are useful in improving our understanding of this issue. We demons...

Manipulability Comparisons of Positional Voting Rules for Large Three-Candidates Elections

Given any positional voting rule (PVR), a characterization of unstable voting situations is provided for three-candidate elections with large electorates. Our contribution to this literature concerns three aspects: (i) a comparison of PVRs via set inclusion of their corresponding sets of unstable voting situations; (ii) a full classification of PVRs according to their vulnerability to coalition...