[EM] Holding byelections with PR-STV

[Jonathan Lundell]

On Sep 16, 2009, at 3:20 AM, James Gilmour wrote:

> Jonathan Lundell  > Sent: Wednesday, September 16, 2009 12:18 AM
>> In fact, a special provision must be made to ensure that previously
>> elected candidates remain elected in a countback. There are at  
>> least a
>> couple of ways to accomplish this. It ends up being a subtle problem.
>
> Jonathan, that's a helpful clarification.  Does OpenSTV include such  
> "special provisions", so that it can cope with "count-back" counts  
> as well as counts where there are "withdrawn" candidates?

No, I don't think it does. And the standard input file format that we  
use doesn't have a provision for marking candidates as protected,  
either (though offhand I can think of a simple way of extending it).

These days, OpenSTV is pretty easily extended (we've moved to a plugin  
architecture), so I suppose the real reason there's no support for  
this is that we don't have any real-world rules to look to.

>
>
>> (It's also worth noting that additional candidates might choose not  
>> to
>> stand, or be ineligible to stand, in the countback, and would need to
>> be marked as withdrawn as well.)
>
> Yes, that would be the expected approach for STV count-back, as it  
> is in party-list PR systems where the casual vacancy is filled by  
> the "next" candidate of the relevant party.
>
> James