[EM] calculating the N matrix in Schulze STV

[Kristofer Munsterhjelm]

On 06/29/2013 11:32 AM, Markus Schulze wrote:
> Hallo,
>
> N[{a,b,c},d] = 169 or Ñ[{a,b,c}, {a,b,d}] = 169 means
> that W=169 is the largest value such that the electorate
> can be divided into 4 disjoint parts T1,T2,T3,T4 such that
>
> (1) Every voter in T1 prefers candidate a to candidate d;
> and T1 consists of at least W voters.
>
> (2) Every voter in T2 prefers candidate b to candidate d;
> and T2 consists of at least W voters.
>
> (3) Every voter in T3 prefers candidate c to candidate d;
> and T3 consists of at least W voters.

What algorithm do you use to distribute the voters in this manner? The 
same voter may increase any of the subset of candidates he prefers to d, 
so it doesn't seem straightforward to determine which candidate's group 
a given voter should be placed into.