[EM] Ultimate SPE Agenda Processing: Sink Swap Bubble

[Forest Simmons]

Kevin,

So far the only comprehensive solution that I see is this version of Chain
Climbing with a sincere runoff between the last pivot and the only
uneliminated candidate.

Without the sincerity check the method will inevitably filter out some (too
many?) good candidates along with the cycle instigators

Lacking an undefeated candidate .


1. Update the (implicit Approval) agenda by sink sorting it pairwise.
2. Let PIvot be the least favorable candidate on this updated agenda.
3. Eliminate friends(Pivot) including Pivot itself.
4. If only one candidate R remains uneliminated, rescue the last Pivot from
the trash, and elect the sincere winner between it and R.
5. Else repeat steps 1 thru 5 until step 4 produces a winner.

Right now I am investigating the following simpler method to see if it can
work almost as well:

1. Let DCACC be the Defense Champion Approval Cutoff Candidate defined as
the minMaxPairwiseOpposition candidate.
2. Elect the winner of a sincere runoff between DCACC and the Approval
Winner determined by approval based on the DCACC cutoff.

That winner will either be the DCACC candidate itself or else the candidate
ranked ahead of it on the most ballots.

If the approval cutoff were inclusive, the DCACC would win too often so
that burial would not be discouraged enough.

If the cutoff were exclusive, the DCACC would be unfairly discriminated
against.

I think the right compromise is to define the DCACC approval to be the
average of its Implicit Approval and its Equal First Whole approval.

It will take some testing to see if this even yields a monotonic method.

So I agree ... we're not done yet. And Mike did bail out too soon!

-Forest


On Mon, Apr 10, 2023, 12:50 AM Kevin Venzke <stepjak at yahoo.fr> wrote:

> Hi Forest and Kristofer,
>
> A couple of old responses. I know Forest has continued to post new ideas.
>
> Kristofer wrote:
> > This is about chicken resistance in general, no? I suspect there's a
> > more general impossibility result hiding here: that methods that are
> > burial resistant and Condorcet (in the way the Smith-IRV hybrids or
> > Friendly is) have to make uncharitable interpretations of ballots that,
> > if they were honest, would imply a very different candidate should be
> > elected. (I have no proof of this, but it seems a reasonable hunch.)
>
> I don't want to rule this out. Although I'm disputing here that chicken
> resistance actually
> is about burial, maybe there's a way to frame it in that way that would
> make sense to me.
>
> I have not studied so many Condorcet methods that (purport to) be
> chicken-resistant. One
> would probably want a way to measure the characteristics of the method
> (beyond simply
> whether it satisfies the CD criterion or some CD criterion). We might look
> to see reduced
> truncation incentive. The difficulty here is that WV methods have, at face
> value, very low
> truncation incentive, lower than Schwartz//IRV. You may end up with the
> conclusion that
> chicken-resistant methods outperform only in very specific scenarios,
> which would not lead
> me to think there is a connection to an impossibility result.
>
> I note also that I dispute that it was warranted to define the CD
> criterion in such a way
> that IRV or any Condorcet method would satisfy it. I've speculated that
> perhaps DSC comes
> closest to the spirit of it. But DSC plainly encourages burial. I guess it
> makes sense: If
> you're going to penalize truncation then sometimes actual burial (order
> reversal) will be
> the result.
>
> Forest wrote:
> > Our method disappoints the faction X responsible for creating the cycle
> by
> > electing Y, the candidate that the burial or truncation insincerely
> helped
> > (by raising or by truncating below) to create the cycle subverting the
> > sincere CW ... namely Z.
> >
> > The sincerity check will actually elect Z ... but most electorates will
> > think the check is too costly... so they will have to be content to
> > disappoint the faction guilty of creating the insincere cycle ... cycle
> > prevention for future elections.
>
> Part of what I want to point out is that you cannot only disappoint the
> faction that
> truncated. You will also disappoint the faction that did what they were
> supposed to do. And
> both factions have the ability to decide to vote differently in response
> to this potential.
>
> This makes it speculative to believe the effect of chicken resistance is
> less truncation.
> It could as easily be that the effect of chicken resistance is more
> favorite betrayal (or
> fewer candidate nominations by the majority). In either event, will there
> be fewer cycles?
> Sure. Will it be because there are only two candidates in the race?
> Possibly.
>
> From an advocacy standpoint, I am disturbed at how close CD takes us to
> IRV's behavior,
> given that probably the easiest criticism of IRV is its failure to detect
> and take into
> account pairwise majorities. Whatever magic a CD method can do by ignoring
> majorities, IRV
> is already doing - and IRV has no truncation incentive, so it's probably
> doing it more
> reliably.
>
> This isn't to say I don't think the chicken dilemma is a problem. I don't
> want someone to
> read my position as that I don't care about it. It's just that I think
> Mike did not give us
> a plausible remedy.
>
> Kevin
> votingmethods.net
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20230410/e806e935/attachment.htm>