I added a version of ranked pairs/winning votes (as I understand it) to the CIVS voting system, though it's a little harder to get to than the beatpath winner result. This is partly because RP seems to be much more expensive to compute, even with some rather effective optimizations I added to incrementally compute transitive closure.
The big quandary I faced was what to do with preferences of equal strength. I don't like random methods because I think they make voters less confident about the results. So I adopted the following rule: a preference is considered as part of the final preference graph if it does not create any _new_ cycles when considered in combination with only _strictly stronger_ preferences. In other words, the final graph might contain cycles, but only cycles that arise because preferences of equal strength create a cycle when they are accepted, whereas each of those preferences individually would not create a cycle. In various trials it seems to work well. I find that the result seems to be more stable than beatpath winner in the sense that individual voters don't perturb the output order as much. But this is not a result that I have methodically tested, just a strong impression. I also find it easier to explain and justify than beatpath winner. Anyone is welcome to try it out on the web site, of course. So I'm curious to know whether this is a variant of ranked pairs that has been explored (or named) previously and whether there are any evident problems with it. -- Andrew ---- Election-methods mailing list - see http://electorama.com/em for list info