[EM] Citation for immunity to strategic voting?

Dave Ketchum davek at clarityconnect.com
Mon Sep 5 17:57:20 PDT 2005

I see some to applaud here:

On Mon, 5 Sep 2005 18:56:32 -0400 Andrew Myers wrote:

> Date: Mon, 5 Sep 2005 18:51:40 -0400
> From: Andrew Myers <andru at cs.cornell.edu>
> To: Stephane Rouillon <stephane.rouillon at sympatico.ca>
> 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).

Another argument for wv over margins - which I already prefer for other reasons.
>>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,
> 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.

I choke on forbidding truncation, for I see that generating excessive noise.

However, I see here ranking all the "plausible" candidates, which I see as 
less pain.  Further, I suspect it does not demand full compliance - seems 
like partial compliance would defend against all but the strongest strategies.

I do choke on runoffs.  Aside from being expensive, they have their own 
problems.  Better to make strategies as difficult as practical and 
tolerate what was close to a tie being pushed the wrong way without the 
strategists getting caught and, hopefully, punished.

> Thanks,
> -- Andrew

  davek at clarityconnect.com    people.clarityconnect.com/webpages3/davek
  Dave Ketchum   108 Halstead Ave, Owego, NY  13827-1708   607-687-5026
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