The Effects on Monotonicity when Combining Alternative Vote with Plurality
We introduce a voting procedure that compounds alternative vote (AV) and the method of plurality. For a three-candidate election, we characterize when an AV election can violate monotonicity. We use this characterization to show that the compound procedure is no more likely (and for certain numbers of voters, strictly less likely) to produce an election that can violate monotonicity. We also show that the voting profiles that can violate monotonicity in an AV election are disjoint from those that can violate monotonicity in an election using the compound procedure. Finally, we find sharp lower bounds for the number of voters required for AV and the compound procedure to yield an election that can violate monotonicity.
Lazowski, A. & Shea, S. (2018). The effects on monotonicity when combining alternative vote with plurality, IMA Journal of Applied Mathematics, 83(3), 514–525. doi: 10.1093/imamat/hxy017