[EM] Just to let you know...

Kristofer Munsterhjelm km_elmet at t-online.de
Sun Jan 15 05:52:04 PST 2023

On 1/14/23 07:26, robert bristow-johnson wrote:

> So when they bleat "Arrow", I respond that a cycle is an unavoidable
> failure, so let's do the best we can with it.  Let's elect the plurality
> winner in that case.  Or elect the IRV winner, or the runoff winner of
> the top-two.  Or if BTR is used, we accept the BTR winner as just as
> good as the plurality winner when there is no Consistent Majority
> Candidate (which is my neologism for the CW).

I think my concern with Condorcet//Plurality is that Plurality is such a 
bad method that if a botched strategy or a natural cycle happens, then 
the result is really going to suck. It's not going to happen often, but 
it would be a good idea to have somewhat less of a failure if it happens.

Doing top two (contingent vote) or IRV if there isn't a Condorcet winner 
is better in almost every respect except for the one: you lose 
monotonicity. As is Forest's summable approximation to Smith-IRV: Each 
candidate has a penalty equal to the combined first preferences of the 
candidates beating him pairwise. Lowest penalty wins.

Even just proceeding with BTR-IRV is better, I'd say, C//P. Or minmax, 
though I would rather prefer Smith: it's somewhat of a guarantee that if 
a cycle happens, you won't elect someone obviously bad (outside the 
cycle). It's too bad that outside of Copeland and BTR-IRV itself, 
there's no really simple Smith mehod; Forest's approximate Smith-IRV is 
about the best simple improvement you can do.

> I'm gonna be quiet now and listen to you guys.  As an 
> activist/schlub, I feel quite privileged to get critique from Markus
> and Kristofer.

Aw, thank you!


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