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

[Forest Simmons]

I have learned a lot from the "hay guys" thread that spontaneously upgraded
into this "hey guys" thread.

Colin Champion made some very helpful points and pointers about the
psychology of what we are involved in. Many similar practical
considerations contributed by all participants.

Several suggestions have been made about how to complete this sentence:

"Lacking a candidate that defeats every other candidate in pairwise
head-to-head comparisons, elect the candidate that ..."

I can live with most of those suggestions ... which is neither here nor
there in the grand scheme of things ... but I hope haven't offended anybody
or discouraged anybody's contributions to these explorations.

Several people have said, "Why not just ...?"

And I thought, "Why didn't I think of that?"

The most promising idea I am currently thinking along these lines goes like
this:

Elect the pairwise undefeated champion ... or lacking such a champion,
elect the winner of the strongest pairwise defeat ... meaning the pairwise
contest with the greatest sum of winner approval and loser disapproval ...
winner approval measured by winning votes ... the number of ballots on
which the winner outranks the loser... loser disapproval measured by loser
abstentions ... the number of ballots on which the pairwise loser is
unranked.

So winning votes plus loser abstentions is my proposal for defeat strength
... not to be used in Rsnked Pairs ... but just in the first and strongest
step of RP ... and then only in the absence of a Condorcet Winner.

For now it's just an idea needing an experimental shake down beyond my
meager manual tests.

But who knows?

-Forest

On Sun, Feb 19, 2023, 10:47 AM Colin Champion <
colin.champion at routemaster.app> wrote:

> I asked Kristofer whether Condorcet+FPTP complied with the Condorcet Loser
> criterion. He replied "probably not" with a sketch proof, and then gave the
> following example.
>
> <quote>
> [preliminary election]
>
> 40: L>C>R
> 42: R>C>L
> 10: C>L>R
>
> R is the Condorcet loser and Plurality winner. (L is the IRV winner.)
>
> Now clone C, the CW:
>
> 40: L>Ca>Cb>Cc>R
> 42: R>Cb>Cc>Ca>L
> 10: Cc>Ca>Cb>L>R
>
> There's no CW, so Plurality elects R, the Condorcet loser. (Incidentally,
> R ties for first in minmax.)
>
> Seems OK. Verified with
> https://web.archive.org/web/20220403135047/http://www.cs.angelo.edu/~rlegrand/rbvote/calc.html.
>
> </quote>
>
> I'd wondered whether Robert didn't have any intellectual commitent to the
> criterion, but had used it in argument against IRV and therefore found his
> options limited.
>
> CJC
>
> On 19/02/2023 17:31, Kristofer Munsterhjelm wrote:
>
> On 2/19/23 16:36, Colin Champion wrote:
>
> "Politicians and the voting public would not accept anything more
> complicated than X" is my own favourite line of argument - but I substitute
> my own value for X(minimax). I know that my judgement is coloured by my
> preferences. There's a surprising degree of dissent over which methods are
> simpler than which, and where the boundary should be drawn. People who deal
> directly with politicians and the voting public can no doubt get closer to
> the truth than people whose interest is predominantly theoretical, but I
> wish there was an authoritative and objective source of information. If
> only some behavioural psychologist was funded to investigate the
> question...
>
> To be finicky, the issue isn't exactly one of simplicity but rather one of
> psychological acceptability, which includes the notions of whether a method
> "makes sense" to the average onlooker, and whether it is seen as conferring
> legitimacy on its winner rather than being an unmotivated piece of jiggery
> pokery.
>
> Notwithstanding all this... you and Robert may well be right.
>
>
> FWIW, I suspect the complexity people are willing to accept depends on
> their trust in the political process in general. For instance, some local
> New Zealand elections use Meek's method, which is complex however you put
> it.[1] And I wouldn't be prepared to explain the pretty messy greedy
> algorithm used to allocate party list top-up seats here (in Norway), but
> people seem to accept it.[2]
>
> I don't think Robert could use minmax because the criterion he's using is
> "if more people prefer X to Y than vice versa, then Y is not elected". That
> seems to imply at least Condorcet loser. I'm not sure, though -- if you're
> particularly critical, you could even say it implies Smith, but I don't
> think Robert had that in mind.
>
> -km
>
> [1] I wonder what the legal language for *that* is... it's basically
> impossible to do by hand.
> [2] IMHO, biproportional apportionment is *much* simpler. I suspect what's
> keeping it from being changed is mostl inertia.
>
>
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