[EM] BTR-like phrasing of Benham

[Richard Lung]

I see you are still eliminating.
It reminds of the Daleks: "Exterminate, Exterminate! EXTERMINATE!"

(It's not democracy.)

Richard L.


On 06/12/2019 23:09, Kristofer Munsterhjelm wrote:
> Here's a BTR-IRV-like phrasing of Benham. The ballot counters would
> probably not appreciate the extra work, but there's a benefit that it
> can easily be used in STV as well:
>
> - When choosing a candidate to eliminate, consider the two candidates A
> and B with fewest first preference votes (A having fewer than B). If A
> wins a runoff against every other remaining candidate, eliminate B;
> otherwise, eliminate A.
>
> This works because if, after some eliminations, X is the CW among the
> remaining candidates, then X will never be eliminated after that point.
> Thus the candidate who remains until the end is the Benham winner. It
> works in STV as well because as long as the election and surplus
> distribution based on first preferences work the way they do in STV, the
> method passes Droop proportionality, no matter what candidates are
> eliminated.
>
> Similarly, transplanting the BTR elimination mechanism onto STV will
> preserve Droop proportionality. I think Rob suggested that the
> eliminated candidate for STV-ME (BTR-IRV's STV analog) should be the
> loser of a Condorcet method's election among the (s+1) candidates with
> the fewest votes, where s is the number of seats remaining to elect
> candidates to. That strikes me as a little too complex, though.
>
> Just basing the method on globally preserving the CW is easier, although
> it might produce somewhat of a centrist bias within each solid
> coalition. Then again, it might not, given how the surplus distribution
> works. E.g. the first solid coalition would elect a global CW if there
> is one among it; but then everybody who voted for this global CW in
> first place after eliminations would be deweighted, so that later "CWs"
> would be biased in the opposite direction, somewhat. It's hard to tell.
>
> Even if it's centrist-biased, that might not be a bad thing. See e.g.
> arguments for deliberately giving the center greater weight in an
> otherwise proportional system to limit unfair kingmaker scenarios.
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