[EM] A few papers on election science I'd like to point out to y'all

[Jameson Quinn]

Yes, I believe that many of these references refer to what is essentially
BTV, which has been known on this list for some time now as a superior
option to STV. I'm happy that it's now in the literature, and don't really
care about naming/precedence.

It's my experience that many prop-rep voting methods can be expressed in
terms of an STV backend. PLACE, Dual Member Proportional, many MMP
variants, etc. can all be seen as just adding options (such as overlapping
seats for MMP and DMP, biproportionality for DMP and PLACE, and partial
delegation for PLACE) on top of STV. You could therefore create new
versions of all of the above by replacing STV with BTV. I think this would
be a small step up — but not worth the additional difficulty of
explanation, in a world that's more used to STV.

2018-02-04 12:22 GMT-05:00 Kristofer Munsterhjelm <km_elmet at t-online.de>:

> On 01/29/2018 02:43 PM, Arthur Wist wrote:
>
>> Hello,
>>
>> Sorry in advanced for the huge load of information all at once, but I
>> think you'll highly likely find the following quite interesting:
>>
>> On how people misunderstood the Duggan-Schwartz theorem:
>> https://arxiv.org/abs/1611.07105 - Two statements of the Duggan-Schwartz
>> theorem
>> https://arxiv.org/abs/1611.07102 -  Manipulability of consular election
>> rules
>>
>> EVERYTHING here:
>> https://scholar.google.com/citations?user=ssb0yjUAAAAJ&sortby=pubdate
>>
>> Some key highlights from that last link above:
>>
>> https://arxiv.org/abs/1708.07580 - Achieving Proportional Representation
>> via Voting [ On which a blog post exists: https://medium.com/@haris.aziz
>> /achieving-proportional-representation-2d741871e78. Better than STV and
>> STV derivatives in all criteria? You decide! ]
>>
>
> From a cursory look at the latter, that looks like Bucklin with a
> STV-style elect-and-reweight system. I wrote some posts about a
> vote-management resistant version of Bucklin at
> http://lists.electorama.com/pipermail/election-methods-elect
> orama.com/2016-December/001234.html and http://lists.electorama.com/pi
> permail/election-methods-electorama.com/2017-September/001584.html, and
> found out that the simplest way of breaking a tie when more than one
> candidate exceeds a Droop quota is nonmonotonic.
>
> The simplest tiebreak is that when there are multiple candidates with more
> than a quota's worth of votes (up to the rank you're considering), you
> elect the one with the most votes. This can be nonmonotone in th following
> way:
>
> Suppose in the base scenario, A wins by tiebreak, and B has one vote less
> at the rank q, so A is elected instead of B. In a later round, say, q+1, E
> wins. Then suppose a few voters who used to rank A>E decides to push E
> higher.
>
> Then B wins at rank q. If now most of the B voters vote E at rank q+1, it
> may happen that the deweighting done to these voters (since they got what
> they wanted with B being elected instead of A) could keep the method from
> electing E.
>
> E.g. A could be a left-wing candidate, B be a right-wing candidate, and E
> a center-right candidate. In the base scenario, A wins and then the B
> voters get compensated by having the center-right candidate win. But when
> someone raises E, the method can't detect the left wing support and so the
> right-wing candidate wins instead. Afterwards, the right-wing has drawn
> weight away from E (due to E not being a perfect centrist, but instead
> being center-right), and so E doesn't win.
>
> Achieving monotonicity in multiwinner rules is rather hard; it's not
> obvious how a method could get around the scenario above without
> considering later ranks.
>
> I'm not sure if rank-maximality solves the problem above. If it doesn't,
> then the above is an example of CM failure but not RRCM failure.
>
> See also http://lists.electorama.com/pipermail/election-methods-elect
> orama.com/2012-January/094876.html and http://lists.electorama.com/pi
> permail/election-methods-electorama.com/2012-February/095188.html for
> another Bucklin PR method that seemed to be monotone.
>
> It's also unknown whether Schulze STV is monotone, though it seems to do
> much better than IRV-type STV in this respect. And I'd add that there's yet
> another (very strong) type of monotonicity not mentioned in the paper as
> far as I could see. Call it "all-winners monotonicity" - raising a winner
> on some ballot should not replace any of the candidates on the elected
> council with anyone ranked lower on that ballot.
>
> (There's a result by Woodall that you can't have all of LNHelp, LNHarm,
> mutual majority and monotonicity. Perhaps, due to the difficulty of
> stopping the monotonicity failure scenario above, the equivalent for
> multiwinner would turn out to be "you can't have either LNHelp or LNHarm,
> and both Droop proportionality and monotonicity"...)
>
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info
>
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