[EM] IRV-Approval, Condorcet-Approval hybrids

[Kevin Venzke]

David,

 --- Dgamble997 at aol.com a écrit : 
> Kevin Venzke wrote:
> 
> >David's method gives me a similar, simpler idea that would seem to be an
> >improvement over IRV. The method would be:
> 
> >1. The voters rank the candidates they would be willing to support, and also
> >place an approval cutoff. (Alternatively, all candidates ranked non-last
> >could be considered "approved.")
> >2. While there is no (voted) majority favorite, eliminate the Approval 
> loser.
> >3. Elect the voted majority favorite.
> 
> I admit my method is complex -simpler would be better. Could you provide an 
> example of your (or Chris's) idea to show how it would discriminate a low 
> utility centrist from a high utility one?

The same way it works in Approval.  Take the "weak centrist" scenario again,
assuming the weak centrist is at the voter median, meaning he is the CW.
In Approval, both the A and C factions have the ability to unilaterally give the 
election to centrist B.  (They cannot support B and also hope for Favorite to
win.)  If a faction chooses not to do this, it means they prefer to take 50/50 
odds of Favorite vs. Worst, rather than a 100% guarantee of weak centrist winning.

In "Approval-Elimination Runoff" (or whatever), the centrist will lose if his
approval doesn't exceed that of either faction's candidate.  He'll win if
his approval is at least 2nd place, because he'll beat the remaining candidate
pairwise by a majority.

Example where B is good enough:
48: A>B | C
3: B | A>C
49: C>B | A

No majority, so A is eliminated, and B has a majority.  If the major factions had
not approved B, B would've been eliminated first and A would win with a majority
over C.

I hope that's clear.


Kevin Venzke
stepjak at yahoo.fr


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