Parliamentary Voting Procedures: Agenda Control, Manipulation, and Uncertainty / 164
Robert Bredereck, Jiehua Chen, Rolf Niedermeier, Toby Walsh
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We study computational problems for two popular parliamentary voting procedures: the amendment procedure and the successive procedure. While finding successful manipulations or agenda controls is tractable for both procedures, our real-world experimental results indicate that most elections cannot be manipulated by a few voters and agenda control is typically impossible. If the voter preferences are incomplete, then finding possible winners is NP-hard for both procedures. Whereas finding necessary winners is coNP-hard for the amendment procedure, it is polynomial-time solvable for the successive one.