DeepAI AI Chat
Log In Sign Up

Manipulability of Single Transferable Vote

by   Toby Walsh, et al.

For many voting rules, it is NP-hard to compute a successful manipulation. However, NP-hardness only bounds the worst-case complexity. Recent theoretical results suggest that manipulation may often be easy in practice. We study empirically the cost of manipulating the single transferable vote (STV) rule. This was one of the first rules shown to be NP-hard to manipulate. It also appears to be one of the harder rules to manipulate since it involves multiple rounds and since, unlike many other rules, it is NP-hard for a single agent to manipulate without weights on the votes or uncertainty about how the other agents have voted. In almost every election in our experiments, it was easy to compute how a single agent could manipulate the election or to prove that manipulation by a single agent was impossible. It remains an interesting open question if manipulation by a coalition of agents is hard to compute in practice.


page 1

page 2

page 3

page 4


An Empirical Study of the Manipulability of Single Transferable Voting

Voting is a simple mechanism to combine together the preferences of mult...

Complexity of Shift Bribery in Committee Elections

We study the (parameterized) complexity of SHIFT BRIBERY for multiwinner...

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. Man...

Manipulation and gender neutrality in stable marriage procedures

The stable marriage problem is a well-known problem of matching men to w...

Bspline solids manipulation with Mathematica

Bspline solids are used for solid objects modeling in R3. Mathematica in...

Beyond the Worst Case: Semi-Random Complexity Analysis of Winner Determination

The computational complexity of winner determination is a classical and ...

Election Manipulation in Social Networks with Single-Peaked Agents

Several elections run in the last years have been characterized by attem...