[EM] A possible solution to SNTV vote-splitting

[Raph Frank]

On Tue, Feb 9, 2010 at 10:42 PM, Kristofer Munsterhjelm
<km-elmet at broadpark.no> wrote:
> Raph Frank wrote:
>> If there are N seats, then you need N/(N+1) of the votes in order to
>> guarantee that the new council will be elected.
>
> Hm, not necessarily, I think. Say you have something similar to:
>
> 10: A1 A2 A3 ... A10 >> B1 B2 B3 ... B20
> 10: B1 B2 B3 ... B20 >> A1 A2 A3 ... A10
>
> Where >> means those above are rated highly, those below low. The B voters
> are spreading their power too thin, and so there will be a lot more
> A-candidates on the council; but the B-voters can decide (unilaterally) to
> zero-rate all B-candidates but B1...Bn (where there are n*2 seats). Then the
> A-voters do the same (exclude all A but A1...An), and the outcome is stable,
> because at that point, neither the A-voters nor the B-voters can improve the
> outcome.

Ahh Ok, so the change assumes that those outside the group hold their
votes constant.

Also, "prefer" means according to the cumulative ballot, it is assumed
to be an honest range ballot?

>> CPO-STV says that if your first choice has a seat, then you can't vote
>> for any of the other seats (subject to surplus transfers)
>
> Ordinary STV doesn't go beyond first choices, either, which I think
> amplifies its chaos.

I was reading a proposal to use an alternative method to decide the
elimination ordering.

PR-STV retains its Droop criterion compliance no matter what order the
candidates are eliminated, as long as elected candidates are not
eliminated.

I think this might have been it (couldn't find an ungated one)

http://preview.tinyurl.com/y8648yt

The idea is that you have a loop where elimination ordering affects
who is subsequently eliminated, which causes chaos, as each stage
causes a change in later changes.

Anyway, his idea is to use borda to decide elimination ordering.