Mike, --- MIKE OSSIPOFF <[EMAIL PROTECTED]> a écrit : > You continued: >> >> In other words, it must *never* be optimal strategy (i.e., be best for >> {a,b}) >> to vote A=B. The problem with this is that most likely the optimal strategy >> will >> be to vote the more viable candidate over the less viable one. >> >> If you insist on this latter property and FBC at the same time, then the >> probability that the winner comes from {a,b} must be totally independent of >> whether you vote A=B, A>B, or B>A. >> >> The latter property is satisfied by "MinGS" ("elect the candidate whose >> fewest >> votes for him in some contest is the greatest") and Woodall's DSC method >> (which >> is not a pairwise count method). > > I reply: > > Just at first glance, that sounds pretty good, guaranteeding that the chance > of the winner coming from {Dean, Nader} is completely independent of how you > order those two. Your ordering of them depends only on which you choose over > the other. Isn't that a further reduction in the lesser-of-2-evils problem? > > I haven't looked at MinGS or DSC, and maybe they have some big disadvantage, > but it's my policy that even the most unlikely solution deserves a look.
Sorry, it would have helped if I had given the "latter property" a name. MinGS and DSC both fail FBC pretty obviously. I'm not currently aware of a method which satisfies FBC and the latter property; I think such a method might have to be equivalent to plain approval. >What an embarrassment. Yes, that's a ridiculous result, when increasing the >A & B voters without bound makes them both lose. Does that clinch it for >MDDA over MMPO? I think it does. (Actually, MMPO's SDSC failure already bothered me quite a bit.) >Which method, MMPO or MDDA, makes it less likely that those LO2E >progressives will regret ranking Dean in 2nd place, instead of in 1st place >with Nader? > >MDDA. I've written a simulation which aims to measure this. I'll have to make the results prettier (and scaled) before I post them, but your conclusion is the same as my simulation's. Here's an excerpt... With four candidates, five factions, 50000 trials, and "A->B" means "win moves from A to B when a strict A>B ranking is introduced by one faction who had tied A and B at the top." Candidate "C" refers to any other candidate. B->C B->A C->A C->B ranked Approval: 0 0 0 0 Schulze(wv): 336 5079 7 0 Schulze(m): 460 5075 251 0 MMPO: 545 5303 0 0 MDDA: 392 4056 0 0 tC//A: 1205 4513 0 0 C//A: 858 4458 363 0 ERBucklin(whole): 787 3023 625 556 For the FBC-satisfying methods, only "B to C" and "B to A" win moves occur. Schulze, ERBucklin, and C//A also have "C to A," and ERBucklin also had "C to B," which is not just favorite betrayal incentive, but nonmonotonic incentive. Two things strike me about this data: 1. Schulze(wv) showed extremely little favorite betrayal incentive. 2. tC//A seems surprisingly poor, despite the intuitive argument that, "even if you sink your compromise, you can still vote for him fully in the approval stage." Kevin Venzke ___________________________________________________________________________ Appel audio GRATUIT partout dans le monde avec le nouveau Yahoo! Messenger Téléchargez cette version sur http://fr.messenger.yahoo.com ---- Election-methods mailing list - see http://electorama.com/em for list info