[EM] Multiwinner methods and summability

[Kristofer Munsterhjelm]

This is a simple question: say that you have a multiwinner method that 
reduces to Condorcet in the single-winner case, and that this single 
winner case uses a Condorcet matrix, so that it's properly summable in 
this case. Then say that the method can be counted in the districts 
using an (n+1) dimension matrix for the multiwinner election where the 
council is of size n.

Is this (hypothetical) method summable? The size of the matrix depends 
(superpolynomially) upon the number of winners to elect, but not on the 
number of voters or candidates.

(Whether or not it's summable, it probably wouldn't be practical in the 
real world; with a parliament or council of 100 candidates, the matrix 
would be 101-dimensional and thus far too unwieldy.)