[EM] Droop proportionality criterion for multiwinner Approval

[Kristofer Munsterhjelm]

How's this for an Approval version of the DPC?

If for a given subset S of the candidates, at least p Droop quotas 
approve of S and there is no greater set that contains S that also is 
approved by at least p Droop quotas, then if this subset has cardinality 
f, at least min(p, f) of these candidates should be in the outcome.

-

The greater set provision is required because otherwise, if everybody 
approved of every candidate, there would be no solution unless the 
council size was equal to the number of candidates - since every 
single-candidate set would be approved by the entire electorate and thus 
deserve to be included.

It would not be a very constraining criterion, I think, and something 
similar might be done to make an Approval version of my monotone divisor 
method.