Date: Mon, 5 Sep 2005 18:51:40 -0400 From: Andrew Myers <[EMAIL PROTECTED]> To: Stephane Rouillon <[EMAIL PROTECTED]> Subject: Re: [EM] Citation for immunity to strategic voting?
On Mon, Sep 05, 2005 at 05:55:01PM -0400, Stephane Rouillon wrote: > Actually as many people will tell you, > this claim is wrong. > > I see that Rob already gave you a counter example. > > Maybe you would like to know that using winning vote as > criteria to make pairwise comparison instead of margins > can make your claim true for strong Condorcet winners > (ones which have a more than 50% majority against every > other candidate). Using margin as a criteria your claim is only valid > for stronger Condorcet winners (having a 2/3 majority against > every other candidate). > > Finally, no method is know to garantee the election of a weak > Condorcet winner against unsincere preferences. This > is understandable because absentees can always alter the balance > against the Condorcet winner and hope to unsincerely create > a cycle containing one of their better choice. > > Hope it helps, > Steph. That's very helpful and makes perfect sense. I guess we could guarantee no weak CW by requiring that voters order all candidates, but this might be seen to be onerous. On the other hand, there will probably be a set of "plausible" candidates and if voters know they should make sure to rank all of them it would help create a strong CW. One could also imagine employing a runoff election mechanism in the case of a top cycle (as Juho suggested) where additionally voters were required to give a total order on all candidates to defend against strategic voting. Thanks, -- Andrew ---- Election-methods mailing list - see http://electorama.com/em for list info
