[EM] (no subject)

[Jameson Quinn]

Your DP and ABE criteria are talking about systems not having a problem
with the chicken dilemma. Unfortunately, while satisfying these criteria is
a good thing if the honest preferences have a chicken dilemma situation
(Two near-clones and one opposition candidate who could beat either but not
both of them); it is also bad in some cases (a three-way near-tie with
sincere bullet-like utilities).

So I suggest you look at how SODA handles the chicken dilemma. Without
satisfying your criteria, I believe that it resolves the underlying problem
of the chicken dilemma better than any other system I know.

JQ

2011/11/1 MIKE OSSIPOFF <nkklrp at hotmail.com>

>  For my definition of 3PD, I should define "discriminate":
>
> A voter discriminates among a set of candidates iff s/he votes some of
> them over others in any order she wants to.
>
> I referred to a method that I call "DP". That stands for Defection-Proof.
> It was proposed by Chris Benham. It doesn't meet CD,
> and I guess that only pairwise-count methods can, but it doesn't fail in
> the Approval bad-example, something that can be said for
> only very few methods.
>
> Definition of DP:
>
> Voting is 3-slot: Preferred, Middle, and Bottom.
>
> Bottom is the default for a candidate not ranked on a ballot.
>
> To rank a candidate other than at bottom is to "approve" that candidate.
>
> If the number of voters approving X but not Y is greater than the number
> of voters approving Y, then disqualify Y.
>
> Among the undisqualified candidates, elect the one preferred on the most
> ballots.
>
> [end of DP definition]
>
> DP meets FBC and 3P, and doesn't fail in the Approval bad-example.
>
> CD is probably too demanding, referring, as it does, to a Condorcet
> candidate.
>
> Maybe a criterion an be written that better reflects the Approval bad
> example (the ABE).
>
> Maybe something like:
>
> If a majority prefer A and B to all the other candidates, and if, A would
> win if the 1st choice supporters of both candidates
> voted both over all the others, then A should win even if A's 1st choice
> voters vote B over the others, but the B
> voters don't vote A over the others.
>
> [end of tentative CD definition]
>
> When I have a good definition to reflect the ABE, I'll call it CD.
>
> As for the criterion that I've previously called CD, I'll call it CCD
> (Condorcet Co-operation/Defection Criterion).
>
> Maybe someone has already posted about this, but Bucklin gives the voter a
> lot more than 3 protection-levels, as I've
> defined that term. It gives the voter as many protection levels as there
> are rank positions in the voter's ballot.
>
> So I'll modify the 3P criterion to say "..at least three...", instead of
> "...three..."
>
> And, if a method, like Bucklin, gives an unlimited number of protection
> levels, then it meets the
> Unlimited-Protection-Levels Criterion, which I abbreviate "UP".
>
> MDDA meets 3P and 3PD, but fails UP. Bucklin meets 3P, 3PD and UP.
>
> But, regrettably, Bucklin fails in the ABE.
>
> Can a method meet UP and not fail in the ABE?
>
> Yes. IRV (= whole) meets FBC and UP, and doesn't fail in the ABE.
>
> I now consider IRV (= whole) to be the best method. Certainly the best for
> public political elections.
>
> Between MDDA and DP, I prefer DP, because I consider the ABE to be more
> important than
> discrimination among candidates protected at a protection-level.
>
> (Below "ABE" means "doesn't fail in the ABE")
>
>
> A criterion compliance chart:
>
> -----------------FBC--------3P-----3PD--------UP----ABE
>
> Bucklin---------Yes--------Yes-----Yes--------Yes----No
> MDDA----------Yes---------Yes----Yes---------No----No
> DP--------------Yes---------Yes-----No---------No----Yes
> MCA------------Yes---------Yes-----No---------No----No
> MAMPO---------Yes---------No-----No----------No---No
> IRV(= whole)---Yes-------Yes-----Yes--------Yes---Yes
>
> Mike Ossipoff
>
> ----
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>
>
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