[EM] Universal Domain

[Richard Lung]

Dear All, 

Dare I say it, it's true anyway, FAB STV can and does differentiate the "two stances" approved and disapproved, "using relative rankings only."
FAB STV ballot looks like any other preference vote. But a last preference counts just as much against a candidate, as a first preference counts for a candidate -- and so on, relatively speaking. 
FAB STV has the same or symmetric counts for election and exclusion. They are combined to give an overall result, in terms of keep values -- an extension of the Meek method practise.

FAB STV doesnt require all preferences to be given. Blank preferences count towards a  NOTA quota, an unfilled seat. In the unlikely event of your just wanting to exclude a candidate, a last preference, leaving the rest blank, would count as much as a first preference, the other way.


Regards,
Richard Lung.




On 12 Sep 2021, at 3:13 am, Forest Simmons <forest.simmons21 at gmail.com> wrote:

universal domain 
In social choice, the requirement that a procedure should be able to produce a definite outcome for every logically possible input of individual preference orderings.

So, all ranked equal is a "logically possible preference ordering." 

The main thing I'm wondering is how to modify ASM (Approval Sorted Margins) to make it more broadly acceptable ... and to perhaps comply with Universal Domain as a bonus.

Here's my best attempt so far:

FIASM Fractional Implicit Approval Sorted Margins: Ballots are ranked preference style with equal rankings and truncations allowed. Each candidate's fractional implicit approval score is the number of ballots on which it is ranked equal top plus half the number of ballots on which it is ranked above at least one candidate, but not ranked top.

The candidates are listed in fractional implicit approval order. While there is any adjacent pair where the fractional implicit approval order contradicts the pairwise (head-to-head) win order, transpose the members of the out-of-order pair with the smallest absolute discrepancy in fractional implicit approval.

The resulting list is a social order that satisfies a reverse symmetry property ... reversing all of the ballot ranking inputs (so that equal top becomes equal bottom [or truncated] and vice versa) reverses the social order output.

Does this method satisfy Universal Domain?

Now, what if optional explicit cutoff marks were allowed to demarcate the three levels (0, 1/2, or 1) of fractional approval. Would that violate Universal Domain? 

If so, then the Oxford definition quoted above is inadequate, since it does not logically rule out optional marks when the lack of any optional mark defaults to a standard ranking, and the only stated requirement is that no standard ranking be unusable.

Thoughts?


El vie., 10 de sep. de 2021 10:56 p. m., Kevin Venzke <stepjak at yahoo.fr> escribió:
> To my mind Implicit Approval (as a method in itself) only satisfies it if you can define the ballot format while discussing only relative rankings. So, for example, if the voter ranks all candidates totally equal to each other (no matter whether they are explicitly so ranked, or the ballot is submitted with all preferences truncated), this can only be allowed to mean that all are approved or that none are approved, since there is no way to differentiate these two stances using relative rankings only.
> 
> Kevin
> 
> 
> Le vendredi 10 septembre 2021, 21:49:14 UTC−5, Forest Simmons <forest.simmons21 at gmail.com> a écrit :
> 
> 
> Does Implicit Approval satisfy Universal Domain?
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> Election-Methods mailing list - see https://electorama.com/em for list info


El 10 sep. 2021 10:56 p. m., "Kevin Venzke" <stepjak at yahoo.fr> escribió:
To my mind Implicit Approval (as a method in itself) only satisfies it if you can define the ballot format while discussing only relative rankings. So, for example, if the voter ranks all candidates totally equal to each other (no matter whether they are explicitly so ranked, or the ballot is submitted with all preferences truncated), this can only be allowed to mean that all are approved or that none are approved, since there is no way to differentiate these two stances using relative rankings only.

Kevin


Le vendredi 10 septembre 2021, 21:49:14 UTC−5, Forest Simmons <forest.simmons21 at gmail.com> a écrit :


Does Implicit Approval satisfy Universal Domain?
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