[EM] Resume: Proportional multi-winner ranked voting methods - guidelines?

[Kristofer Munsterhjelm]

On 06/04/2017 10:07 AM, Juho Laatu wrote:
>> On 04 Jun 2017, at 07:55, VoteFair <electionmethods at votefair.org>
>> wrote:
>>
>> Yes, "proportional multi-winner Condorcet" has no clear,
>> unambiguous meaning beyond the criteria for identifying the winner
>> of the first seat.
>
> Yes, it is not easy to say which methods should fall in the
> "proportional multi-winner Condorcet" category. I also note that even
> if it would be a requirement that the first seat shall go to the
> Condorcet winner, if one exists, it is quite possible that the
> Condorcet winner would not be elected if there are two seats. (e.g.
> when there are two big parties, left and right, and one small
> centrist party with a Condorcet winner)

The LCR example is a concrete example that giving the first seat to the 
CW makes the method fail Droop proportionality. E.g.

43: L>C>R
41: R>C>L
  6: C>L>R

number of voters = 90, Droop quota for two seats = 30, so both L and R 
should be elected, but C is the CW.

For larger assemblies, it might still be a good idea to give a few of 
the seats to winners chosen by a multiwinner method with few seats, or a 
single-winner method. Doing so would make centrists the kingmakers in a 
kingmaker scenario, rather than minor parties on one wing.