[EM] VoteFair representation ranking recommended for Czech Green Party

[Markus Schulze]

Hallo,

Kristofer Munsterhjelm wrote (2 May 2010):

> Perhaps there's a better method still than Kemeny,
> say a method that is at least as good on average
> and satisfies clone independence (or perhaps IPDA,
> etc).

My aim was to find an election method that is
cloneproof and that usually produces winners
with weak worst defeats. I believe that the
maximum, that you could ask for, is that the
winner is always chosen from the "MinMax set".
See section 9.1 of my paper:

http://m-schulze.webhop.net/schulze1.pdf

In section 3.6.1, the MinMax set is {A,C,D}.
However, when we add the Pareto-dominated
candidate E, then the MinMax set is {B}.

This demonstrated that IPDA and the desideratum
that the winner is always chosen from the
MinMax set are incompatible.

*********

Kristofer Munsterhjelm wrote (2 May 2010):

> That would be Condorcet with dual dropping, and the
> organization is the MKM-IG: http://www.mkm-ig.org/
> I think Schulze said the method might not necessarily
> be cloneproof: the idea would be something like that
> in the base scenario, the Schulze winner is best, but
> then, when you introduce (or remove) a few clones,
> the Tideman winner becomes "better" and so it switches.

I believe that this method also might not necessarily be
monotonic.

Example: Candidate A is the Schulze winner. Candidate B
is the Tideman winner. Condorcet with dual dropping
chooses candidate A.

Suppose some voters rank candidate A higher. Then, as
the Schulze method is monotonic, candidate A is still
the Schulze winner. However, it is possible that the
Tideman winner is changed from candidate B to some
other candidate C and that Condorcet with dual dropping
chooses candidate C.

Markus Schulze