[EM] Proportional election method needed for the Czech Green party - Council elections

[Markus Schulze]

Dear Peter Zbornik,

> Is the winner of a single-winner Schulze election always
> in the set of winners of a Schulze-STV election, if the
> same ballots are used for both elections?

If more than one seat has to be filled, then the winner
of the Schulze single-winner election method is not
necessarily in the winning set of the Schulze STV method.

*********

> If the answer to the question in my email below is no or
> if the vice presidents sometimes are not members of the
> set of Schulze-STV winners (which I guess can be the case
> even in a council with 7 members, one prezident and 3 VPs),
> then I can imagine that there could be a method, which
> elected the rest of the council members after the the
> president and vice presidents have been elected using
> Schulze proportional ranking.
>
> Such an election method would sacrifice a proportionality
> in the council in order to achieve proportionality in the
> ordered set of the president and the vice presidents.
>
> The election of the rest of the council members would be
> done to maximize the proportionality of the elected council,
> maybe by using a modified version of Schulze-STV, where the
> president and vice presidents would be considered elected
> to the council at the start of the STV election, using the
> same ballots as for the Schulze proportional ranking election.
>
> Thus, the rest of the council members would be elected in
> such a way, that the council would be as much proportional
> as possible.
>
> Would your software be able to handle this problem (possibly
> after some slight modification)?
> What methods would you recommend for this scenario?

I recommend:

--the president is the top-ranked candidate of the Schulze
  single-winner ranking,
--the vice president is the second-ranked candidate of the
  Schulze single-winner ranking,
--the other members of the council are chosen by the Schulze
  proportional ranking method so that proportionality is
  maximized.

My software could handle this problem (after some slight
modifications).

Markus Schulze