[EM] Hay guys, look at this...

[Forest Simmons]

Thanks, Kevin ... your wide experience is very valuable.



On Sat, Feb 18, 2023, 2:18 PM Kevin Venzke <stepjak at yahoo.fr> wrote:

> Hi Forest,
>
> Le samedi 18 février 2023 à 13:19:10 UTC−6, Forest Simmons <
> forest.simmons21 at gmail.com> a écrit :
> > Here's a simple, acceptable method that beats many elaborate Condorcet
> proposals including
> > Copeland,Baldwin, Black, Nanson, MinMax, and many others. If it turned
> out that twenty
> > percent of Condorcrt election had cycles in a certain odd ball
> electorate, it would still
> > be a credible, upstanding choice.
> >
> > It has a natural segue from the simplest definition of a Condorcet
> Winner into what to do
> > if there is no CW:
> >
> > A Condorcet Winner C is a candidate that is unbeaten pairwise. This
> means that for any
> > other candidate X, the number of ballots on which C outranks X is
> greater than the number
> > of ballots on which X outranks C.
> >
> > In other words, C has a positive margin of support compared to any other
> candidate X.
> >
> > If there is no candidate with a positive margin of support compared to
> every other
> > candidate, then elect the candidate with the single greatest margin of
> support relative to
> > any other candidate.
>
> I'll call this method C//MaxMargin or C//MM.
>
> One reason I can "live and let live" in regards to C,FPP is that it at
> least satisfies the
> Plurality criterion. I think methods that fail this will be hard to
> propose.
>
> (I also think that being likely able to guess which candidate will benefit
> from a burial
> strategy in C,FPP might at least create some stability there, even if the
> ultimate result
> might be compromise incentive / nomination disincentive, whenever voters
> perceive that
> supporters of the FPP winner have a burial strategy that can't be defended
> against in any
> other way. Put differently, I don't think we would see backfiring burial
> strategies under
> C,FPP, due to the one-sidedness of which voters would want to try burying.)
>
> Realistically C//MM resolves cycle scenarios by electing the candidate
> with the biggest win
> over the weakest candidate. (The winning score probably won't come from a
> match-up between
> strong candidates.) This gives it a good share of the truncation incentive
> seen under
> C//Approval, as it's very clear that adding a lower preference for some
> candidate could
> hand them the win.
>
> But (experimentally) C//MM doesn't see C//A's reduction in burial
> incentive, perhaps
> because you are using the margin, so burial can be used to undermine a
> candidate even if
> you don't defeat that candidate. This is also easy to imagine: A few
> random voters casting
> insincere votes burying a frontrunner could certainly be enough to take
> the win away from
> them.
>
> When it comes to compromise incentive, C//MM is considerably better than
> C,FPP, although
> hardly amazing. Compromise incentive is most relevant to the concerns
> about the use of FPP
> in the method, so perhaps C//MM accomplishes its mission.
>
> Kevin
> votingmethods.net
>
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