On Tue, Sep 8, 2009 at 3:18 PM, Kristofer Munsterhjelm<[email protected]> wrote: > Which one is preferrable? One might, in a way, say that the two are > equivalent. If your preferences are > > A > B > C > D > > and the poll is > > 100: C > 98: B > 90: D > 20: A, > > then voting {A, B} is an offensive strategy from the point of view of A (you > vote B to increase the force against C), but a defensive strategy from the > point of view of B (you vote for A so your vote of B won't hurt A). The only > real difference is which is the "least of two evils" - since B is, B's point > of view is the true one, and this is a defensive strategy.
You need to give info on utility too to determine optimal strategy. You can go through each tie in order of probability. Tie 1: C,B You should vote for B. Tie 2: C.D You should vote for C. However, voting for C weakens your vote in tie 1, so it is better not to vote for C (as tie 1 is much more likely than tie 2). Tie 3: B,D Your vote for B is correct for this one, so no change. Tie 4: C,A You should vote A Tie 5: B,A This is slightly less likely than C,A. Your vote for A is more likely to cause A to beat C than A to beat B. The rest of the tied don't matter. The best vote is likely B+A. The rule could be something like "vote for the best of the top-2 and the highest polled candidate who you prefer to the expected winner". It is highly likely that the vote between the top-2 will be the only one that matters, so the vote is reasonably optimal. The 2nd vote falls into the tie 4 vs tie 5 category. ---- Election-Methods mailing list - see http://electorama.com/em for list info
