[EM] Rethinking Burial Detection Runoff

[Forest Simmons]

First a definition:

A candidate X is an enemy of a pair if it beats both of its members.

New Method:

Elect the CW if there is one.

Else elect the sincere winner of the strongest pair that has no enemies, if
there is such a pair.

Else elect the sincere winner of the pair whose enemy first place count  is
smallest.

fws

On Thu, Jun 15, 2023, 1:17 PM C.Benham <cbenham at adam.com.au> wrote:

>
> On 15/06/2023 7:17 pm, Kristofer Munsterhjelm wrote:
>
> > James Green-Armytage has another suggestion for deterring burial:
> > https://www.jamesgreenarmytage.com/dodgson.pdf
> >
> > I haven't read it in detail, so perhaps the devil's in the details
> > about "plausible assumptions about how candidate decide". But what do
> > you think of that method?
>
> In an earlier article James-Green Armytage discussed different
> Condorcet-IRV  methods, naming them all after people. I think there was
> Tideman, Woodall and "Benham".
>
> Tideman (and "Smith-AV") fails Mono-add-plump and Mono-append. And both
> Tideman and Woodall are more complicated than Benham.
>
> https://www.votingmatters.org.uk/ISSUE29/I29P1.pdf
>
> The "one round version" of what he is now calling "Limited-Round
> Dodgson-Hare" is the same as Benham except that it specifies a
> "voluntary candidate withdrawal" option
> and says nothing about whether equal-ranking should be allowed or how it
> should be handled.
>
> I don't like candidate withdrawal options because I think the result
> should be determined as much as possible by voters via their ballots
> versus the machinations of candidates.
>
> And for a practical proposal I don't like allowing above-bottom
> equal-ranking because it makes the method more complicated and/or more
> vulnerable to Pushover strategy.
>
> But if it insisted on, then equal rankings (say A=B) should be
> provisionally interpreted as giving an equal fraction of a vote summing
> to 1, in this case half a vote each to A and B.
>
> Then for the purpose of deciding which if any gets eliminated the A=B
> ballots should all be interpreted as giving a whole vote to whichever of
> the two had the higher tally on the
> fractional basis and nothing to the one that had the lower tally.
>
>  From the article you linked you linked to:
>
> > Further, Green-Armytage et al. (2016) and Durand et al. (2016)
> > both prove that for most single-winner voting rules including Hare,
> > adding a provision to elect
> > the Condorcet winner when one exists can never make the rule
> > vulnerable to strategy in cases
> > where it was not vulnerable already.
>
> I'm a bit sceptical about that. I would have thought that it would make
> Hare (aka the Alternative Vote aka IRV) less vulnerable to Compromise
> but a bit more vulnerable to Burial.
>
> In terms of criterion compliances the price we pay for gaining Condorcet
> is that we lose Later-no-Help, Later-no-Harm and Mono-add-Top.
>
> Chris Benham
>
>
>
>
>
> On 15/06/2023 7:17 pm, Kristofer Munsterhjelm wrote:
> > On 6/15/23 07:47, Forest Simmons wrote:
> >> Chris,
> >>
> >> I like your new Condorcet method, and consider it to be a much more
> >> practical suggestion than any of my sincere CW finder ideas currently
> >> in progress.
> >>
> >> The ballot profile you provided to illustrate your LV Sorted Margins
> >> burial resistant method, ended up electing A, which we considered to
> >> be better than electing B, because we thought that with some positive
> >> probability the ballot profile might be a result of the B faction's
> >> insincere order reversal .... changing sincere 44 B>A to 44 B>C, i.e.
> >> the B faction burying A under C ... so that electing B, like just
> >> about every other method under the sun, would encourage bad behavior.
> >>
> >> Is it insulting to voters to build in safe guards that make insincere
> >> truncations or burials less likely to pay?
> >>
> >> Is it insulting to lock your front door when leaving town for a few
> >> dsys?
> >
> >> Going outside the strict Universal Domain by allowing truncations,
> >> equal rankings, approval cutoffs, or other levers, offer additional
> >> expressiveness that can reduce incentives for burial, compromise, etc.
> >
> > James Green-Armytage has another suggestion for deterring burial:
> > https://www.jamesgreenarmytage.com/dodgson.pdf
> >
> > I haven't read it in detail, so perhaps the devil's in the details
> > about "plausible assumptions about how candidate decide". But what do
> > you think of that method?
> >
> >>
> >> I've been experimenting with how far we can get with two sets of
> >> ballots ... one possibly strategic set, for the purpose of determing
> >> the finalists and runoff order ... and the other set dedicated solely
> >> to the kind of runoff that elects the sincere CW whenever there is one.
> >
> > This is still an interesting venue, of course. I've updated the
> > Electowiki page about Condorcet loser to include information that a
> > manual runoff method always passes honest Condorcet loser (assuming no
> > drop in turnout).
> >
> > At some point I would like to do a minimum strategy evaluation of
> > methods with two rounds, but I've currently been occupied with
> > cleaning up some other code in my election simulator quadelect so that
> > I can automatically check for clone failures, monotonicity, etc. the
> > same way I can check for strategy failures; and so that I can classify
> > strategy failures as burial, compromise, or other.
> >
> > Maybe, eventually!
> >
> > -km
>
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