Jameson Quinn wrote:
I've been thinking recently about systems which enforce chiral symmetry, making condorcet ties impossible. While it is possible to "solve" the truncation/burial problem (eg, between two near-clones who split a weak majority) in this way, I have not been able to come up with an acceptably simple system. The closest I know of is "tournament seeding"-style, condorcet-compliant (though not necessarily condorcet-based) systems, where only certain pairwise races are considered. In such systems, burial/truncation is a nonstrategy, period.
I think I read somewhere that elimination tournament methods must fail monotonicity. I do know that runoff-type elimination based on weighted positional methods (e.g. IRV being based on Plurality, and Borda-elimination being based on Borda) must fail monotonicity.
Possible monotone methods might be based around Bucklin-type counts, or perhaps something as simple as Smith,Plurality (not very good in practice) or Smith,Approval.
There's also "first preference Copeland" (each candidate has penalty equal to the number of times those that beat it pairwise appear in top rank), BPW (if there is a cycle, elect the candidate that beats the Plurality winner by the greatest amount), and Smith,IRV, but while resistant to burial strategy, none of these methods are monotone.
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