[EM] Top-two Approval Pairwise Runoff (TTAPR)

[Monkey Puzzle]

Chris's suggestion is a good one, though in some ways the original idea has
come full circle.

His suggestion is now reduced to a form of Condorcet completion.

The primary difference from Smith//Approval is that unless the Smith Set is
explicitly required, the winner could potentially come from outside the
Smith Set.

In the example below,

40 C
32 A >> B
28 B >> A

A is the CW and the completion rule is not necessary.  But I can imagine
that there might be situations where a determined CD betrayal by B voters
could force the approval two-seat parliament runoff and prevent A from
being one of the contenders.

 Frango ut patefaciam -- I break so that I may reveal

On Fri, Nov 11, 2016 at 11:18 PM, C.Benham <cbenham at adam.com.au> wrote:

> The "deweight  to zero" option would be best for avoiding an extra easy
> Push-over incentive.
>
> With voters being allowed to rank both above and below an approval
> threshold, this a one-ballot per voter and one trip
> to the polling station version of an earlier suggestion of mine for a 2
> trips to the polling station method using simple Approval
> ballots.
>
> But then we have a method that can badly fail Condorcet and fails FBC.
>
> I suppose if  we don't mind a kludge fix it to meet Condorcet:
>
> *Voters submit rankings with an approval threshold (Default is all
> candidates ranked above equal-bottom are interpreted as approved).
> Elect the CW if there is one.
> Otherwise elect the pairwise winner between (among members of the Smith
> set?)  the most approved candidate A and the candidate
> most approved on ballots that don't approve A.*
>
> Chris Benham
>
>
>
>
> On 11/12/2016 10:51 AM, Forest Simmons wrote:
>
> Very good!  And it works for a variety of Proportional Representation
> methods, whether you deweight the ballots to 1/2, 1/3, or even totally
> deweight to zero, so that no ballot that approved the first finalist has
> any weight at all in deciding who the second finalist is.  That may be the
> simplest method.
>
>
> On Fri, Nov 11, 2016 at 10:13 AM, Monkey Puzzle <
> araucaria.araucana at gmail.com> wrote:
>
>> In this chicken dilemma defection situation, the As and Bs could add
>> preferences below the approval cutoff:
>>
>> 40 C
>> 32 A>>B
>> 28 B>>A
>>
>> Both groups defect from each other, but assign their rival a higher
>> preference above other disapproved candidates.
>>
>> C and the larger first choice of A or B are the two parliament seats, and
>> the disapproved preference helps that candidate win.
>>
>>  Frango ut patefaciam -- I break so that I may reveal
>>
>> On Fri, Nov 11, 2016 at 12:21 AM, Kristofer Munsterhjelm <
>> km_elmet at t-online.de> wrote:
>>
>>> On 11/11/2016 01:48 AM, Forest Simmons wrote:
>>> > Some of the replies are taking the subject line too literally.  We're
>>> > not talking about top two runoff, but two member PR runoff.  we find
>>> out
>>> > who the two member parliament would be then pit those two against each
>>> > other.
>>> >
>>> > So
>>> >
>>> > 40 C
>>> > 32 A>B
>>> > 28 B>A
>>> >
>>> > Suppose that we use PAV with implicit approval
>>> >
>>> > The A is the first member in the two member parliament.
>>> >
>>> > The two factions that supported A get their weights cut in half, so C
>>> is
>>> > the second member.
>>> >
>>> > The runoff is between A and C, not between A and B, as some people are
>>> > assuming.
>>> >
>>> > If the B faction defects, then the two members of the pariliament would
>>> > be B and C, and the pairwise winner would be B, so the method does not
>>> > satisfy CD.
>>>
>>> On a more intuitive level, that isn't too surprising. Suppose you have a
>>> Bush-Nader-Gore situation. The runoff doesn't help the voters who want
>>> to know whether to vote {Nader, Gore} or {Nader}, since if they vote
>>> only Nader, Bush and Gore may go to the runoff (i.e. Nader loses). On
>>> the other hand, if they do vote {Nader, Gore}, and Gore is picked for
>>> the first winner, then their ballots will be deweighted and Nader
>>> probably won't come in second anyway.
>>> ----
>>> Election-Methods mailing list - see http://electorama.com/em for list
>>> info
>>>
>>
>>
>
>
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info
>
>
>
>
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20161114/10a9d19b/attachment-0001.htm>